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SixEight
08-07-2011, 11:01 AM
I had an interesting reply on another forum by rsilvers about the possibility of a 6.8 bullet (supposedly being up to 0.2780 in diameter) being too large for the 6.8x43 chamber with a 0.2775 throat.

While I DO NOT WANT TO START A FLAME WAR or pissing contest, I thought I'd see if I could find any info to support or refute this claim. I searched the web quite a bit for anything related to 6.8 and a 0.2775 throat and a 0.2780 bullet but not surprisingly only found the post I'm referencing below. Maybe I didn't look in the right place or maybe the information is just wrong. That's why I'm posting this so if there is any incorrect information it will hopefully get quickly nipped in the bud.

It's pretty obvious the source of the person's bias is to see the another cartridge succeed over the 6.8 so I take most of what he says with a grain of salt. That's fine, I own a 6.8 so I have a bias to see this cartridge succeed.



That chamber is listed as having a 0.2775 throat. The 6.8 bullet is up to 0.2780.

A tight throat may be ok for certain competition and bench rest rifles, but for a combat style rifle, one should not consider a throat less than the SAAMI spec of 0.2781 because one never wants a situation where it is possible for a bullet to be larger than the throat - or even too close as carbon could be present.

The SAAMI chamber, while it would benefit from some extra lead, has the 0.2781 throat going for it - which will keep pressures down compared to the tighter throat on some attempts at updating the chamber.

If I were making 6.8 rifles, my first choice would be a SPC-II chamber but I would make sure it is a 0.278 or larger throat.

I would take a SAAMI chamber such as in the Ruger over an SPCII or 6.8x43 chamber with a 0.2770 or 0.2775 throat.

68WJ
08-07-2011, 11:15 AM
It is all about tolerances. There are A LOT of 6.8x43 chambers floating around with no issues and many like the performance. You have to remember that these are coming from a specialty company with a focus on this particular area. A large production company is more concerned with the masses and having that extra margin for what-if's.

Similar to if you buy a car off a dealer lot, there are many compromises present to attempt to make a car that will meet the majority's likes. If you take said car and want to run a rally race with it, you will need to change some things. Those changes won't automatically make it good at a drag race either. Performance usually means eliminating compromise for a specific goal.

Let Freedom Group continue to make 6.8's with a larger throat. It won't hurt my feelings and won't hurt ARP. Now, spreading information that supposes the ARP is problematic, all the dead hogs and deer can't hear.

346CI
08-07-2011, 11:36 AM
I had an interesting reply on another forum by rsilvers .

I quit reading after this, LOL.

marinesg1012
08-07-2011, 11:59 AM
None of the .277 caliber bullets I have measured came close to .2780

And I have two of the 6.8x43 chambers and have had no issues with either....

John A.
08-07-2011, 12:19 PM
Not having a dog in the fight from the quote / topic you linked above, apparently someone didn't take into consideration that a gun that shoots .223, the bullets for them don't measure .223" [rolleyes]

Just sayin.

constructor
08-07-2011, 01:48 PM
There seem to be thousands out there(many more than 300AACs) not having problems so it's just Slivers and his typical theroretical lab BS with no experience to back it up.
If he knew anything at all he would know many match chambers are designed with the exact same bullet dia leade like .277, .264, .308 without even the extra .0005 dia.
Most 6.8 bullets measure .2765, only Sierra is a full .277 but remingtons cheap 115 FMJs may be oversize.
However since I use those cheap Rem fmjs to test every rifle before it leaves I know they work just fine. I'll take a wild assed guess that Slivers has NEVER shot a rem bullet through one of our barrels. Again just more of his stupid ass theories.

The funny thing is the chamber that Remington submitted to SAAMI and Barrett was chambering back in 04 and 05 was the chamber that was shaving rings of copper off of the SSA bullets and causing a restriction and blowing primers during military testing. I designed the DMR chamber to fix that little issue, the 6.8x43 is larger than the old DMR chamber due to the thickness of SSAs necks.

rsilvers
08-07-2011, 02:13 PM
This is not something that is a debate or opinion, just a fact. As you can see in this drawing, bullets may be up to 0.278:

http://www.saami.org/PubResources/CC_Drawings/Rifle/6_8mm Remington SPC.pdf

This is why Remington made the 6.8 SPC throat 0.2781 minimum.

Now in the real world, few bullets will be over 0.2773. But, why would you want the bullet even that close to the throat when it leaves no room for carbon? Also, bullets are not in the case mouth perfectly straight - so they rub and stuck when you chamber them cartridges.

And regardless of if a bullet actually gets stuck in the chamber or not, tighter throats have more pressure, as proven in this article:

http://www.border-barrels.com/articles/Pressure_Trials_Consortium.htm

(http://www.border-barrels.com/articles/Pressure_Trials_Consortium.htm)I am aware that some 308 chambers are 0.3085 when the bullet can be 0.309, but that raises pressure and increases the chances of a stuck bullet in 308 also. But sure, you want the build a Palma rifle - that is what you use. Combat or self-defense rifle? Not so much. Also it is more common in bolt actions.

Constructor said it was his opinion that these tight-throat chambers can handle pressure better than the SAAMI chamber. That is not likely, as a tight throat seems to cause a greater pressure increase than a short throat. If you have a 6.8x43 or DMR chamber - and your goal is a combat or self-defense rifle rather than a competition rifle, I would look into reaming it to make sure the throat is not too tight.

And certainly if you try to get a new standard into SAAMI, submit the Bison chamber.

TackDriver68
08-07-2011, 02:44 PM
I quit reading after this, LOL.

Amen. Shame there isn't a rule that would allow admins here to ban trolls.

constructor
08-07-2011, 02:46 PM
As I said before, I can get 2800fps from a Rem 115gr fmj out of a 16" barrel with our 6.8x43 chamber without blowing primers.
Try that in a Remington barrel Slivers and get back to me.

BTW did you see the actual 6.8x43 chamber drawing that Tim sent to Doc?
If you did not you are assuming a lot.

SixEight
08-07-2011, 02:47 PM
If this was an issue for hot ammo wouldn't manufacturers be aware of it? And I'm sure they're running tighter tolerances anyway or we would've heard of problems by now. For ammo not loaded hot wouldn't any increase in pressure at the throat be negated by a larger freebore?

I figured it was a half-truth worst case scenario type of post. I was just a little concerned if there was any ammo that could be unsafe. I just bought a new barrel from ARP but don't regret it.

It does irk me when somebody comes in trolling and veals on your post with that stuff which seems to be happening a lot on other sites and I'm surprised he hasn't been warned.

Jamesb74
08-07-2011, 02:48 PM
I will only say this once. Keep the personal attacks out of this. Bring facts or at least an educated opinion to the discussion without being inflammatory. If you don't like the arguments or the way someone says something then stay out if the thread.

This goes for everyone!

rsilvers
08-07-2011, 03:01 PM
As I said before, I can get 2800fps from a Rem 115gr fmj out of a 16" barrel with our 6.8x43 chamber without blowing primers.
Try that in a Remington barrel Slivers and get back to me.

That is a http://en.wikipedia.org/wiki/Red_herring because the barrels would differ in other ways besides just the chamber. All we need to know is that making the throat a smaller diameter increases pressure. So if you have a 0.2780 or larger throat, pressure would drop even more.

http://www.border-barrels.com/articles/Pressure_Trials_Consortium.htm



BTW did you see the actual 6.8x43 chamber drawing that Tim sent to Doc?
If you did not you are assuming a lot.

I was referring to your post here:

http://68forums.com/forums/showthread.php?18458-6.8-chambers-SAAMI-SPCII-DMR-6.8x43-Noveske-Mod-1

"(2007)6.8x43 DMR (DMR)- has a .095 freebore, .277 dia and a .305 neck diameter it was designed to correct the bad 80 degree cone angle and be a little more accurate in stainless match barrels because of the shorter freebore and .277 dia leade. Only used in ARP stainless match barrels.

(2009) 6.8x43- has a .095 freebore, .2775 dia with the correct 45 degree cone angle and a .3085/.309 neck."

If the drawing differs from what you claimed, it would be good to let us know. Thanks.

rsilvers
08-07-2011, 03:11 PM
If this was an issue for hot ammo wouldn't manufacturers be aware of it? And I'm sure they're running tighter tolerances anyway or we would've heard of problems by now.

You can look around in that paper I posted, convert BAR to psi, and predict what is likely. It seems like in 308 going from a 0.307 to a 0.3085 throat is about a 300 bar difference (2900 psi). If we assume the difference is linear, then from a 0.307 to a 0.308 would be about 2000 psi. On a smaller bullet like 6.8, the difference may be greater - and it is easily believable that the difference between a 0.277 and a 0.278 throat is up to 2000 psi - which is about 500 psi greater in significant than the difference between a SAAMI lead is to a 0.114 SPC-II lead if both were fixed at 0.278 diameter.

rsilvers
08-07-2011, 03:13 PM
For ammo not loaded hot wouldn't any increase in pressure at the throat be negated by a larger freebore?

Yes, it is a wash, thought tighter throat diameters are more likely to get stuck bullets if you extract a live round - especially because ammo does not have perfect runout (bullets are in the brass at slight angles).

Publius
08-07-2011, 03:27 PM
Most 6.8 bullets measure .2765, only Sierra is a full .277 but remingtons cheap 115 FMJs may be oversize.

This one fact alone seems to make the continued agenda of rsilvers on various forums to discredit the improvements that have been made to the 6.8 that much more obvious. The whole point of the OP was that silvers made a claim that the 6.8x43 could not support the hypothetical .2780 max bullet size. H's statement above clearly refutes that with the fact that most bullets that we will use are smaller than the .2775 diameter (even the Sierra bullets).

This whole "issue" seems to be nothing more than another attempt to start a fire where real life practical use of the 6.8x43 has yet to find one.

constructor
08-07-2011, 03:27 PM
That is a http://en.wikipedia.org/wiki/Red_herring because the barrels would differ in other ways besides just the chamber. All we need to know is that making the throat a smaller diameter increases pressure. So if you have a 0.2780 or larger throat, pressure would drop even more.

http://www.border-barrels.com/articles/Pressure_Trials_Consortium.htm




I was referring to your post here:

http://68forums.com/forums/showthread.php?18458-6.8-chambers-SAAMI-SPCII-DMR-6.8x43-Noveske-Mod-1

"(2007)6.8x43 DMR (DMR)- has a .095 freebore, .277 dia and a .305 neck diameter it was designed to correct the bad 80 degree cone angle and be a little more accurate in stainless match barrels because of the shorter freebore and .277 dia leade. Only used in ARP stainless match barrels.

(2009) 6.8x43- has a .095 freebore, .2775 dia with the correct 45 degree cone angle and a .3085/.309 neck."

If the drawing differs from what you claimed, it would be good to let us know. Thanks.
That is right, that is my chamber design to give the maximium accuracy and performance(velocity) to hunters, civilians, LEO.
I sent 5 uppers to some Navy guys in San Diego a few months ago, just plain old light weight 16" barrels with our standard chamber.
The head honcho called to say he was getting 3/8" groups with Hornady 110gr HPBT factory loaded ammo, so that is what is possible from someone who knows how to shoot.
As for the design Tim sent Doc, I have no idea. We talked about it that night after Doc called Tim, we discussed what we thought would be best for a pure mil chamber and I can only assume Tim emailed that info to Doc. What Doc decided to submit or change or throw in the trash only Doc knows and I don't care.
Since then it is a complete waste of my time to think what the mil might do, I'd be better off running around and around in circles.

rsilvers
08-07-2011, 03:32 PM
This one fact alone seems to make the continued agenda of rsilvers on various forums to discredit the improvements that have been made to the 6.8 that much more obvious. The whole point of the OP was that silvers made a claim that the 6.8x43 could not support the hypothetical .2780 max bullet size. H's statement above clearly refutes that with the fact that most bullets that we will use are smaller than the .2775 diameter (even the Sierra bullets).

Yes, most are smaller than that. Manufacturing tolerances are on a gaussian distribution curve. Few of them will be at the outer limits, and bullets over 0.278 must be rejected by the maker as out of spec.

6.8 has been improved - the SPC-II "Bison" chamber has the 0.114 throat length, which is good, without breaking the 0.278 throat diameter that was correct on SAAMI.

constructor
08-07-2011, 03:34 PM
Yes, it is a wash, thought tighter throat diameters are more likely to get stuck bullets if you extract a live round - especially because ammo does not have perfect runout (bullets are in the brass at slight angles).
Out of thousands of barrels sold I have not had 1 customer call up and say I had a bullet get stuck in the throat when I extracted the case...not 1.
Even the tightest DMR with a .305 neck and .277 throat that wasn't a problem the only problem with those was when SSAs necks grew to .309 in the summer of 2009.
The neck of the chamber has since been changed to allow variances in SSAs manufacturing.

rsilvers
08-07-2011, 03:44 PM
That does not surprise me.

It may be that your throats are not made to the minimum size on the drawing. Generally production reamers are ordered 0.0015 larger than the drawing.

The problem is when a min chamber encounters a max bullet.

sfsmedic
08-07-2011, 03:46 PM
Theory with no real world experience to back it versus reality based testing and 1000's of happy customers who have no complaints, tough decision.

Also remember empirical testing is only considered good and feasible until it's disproven. Seems to me reality based testing has disproven your theory yet you continue to refer to the old.
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TackDriver68
08-07-2011, 03:48 PM
That does not surprise me.

It may be that your throats are not made to the minimum size on the drawing. Generally production reamers are ordered 0.0015 larger than the drawing.

The problem is when a min chamber encounters a max bullet.

Do you have any credible evidence this has ever actually occurred in the real world? Yes or no?

rsilvers
08-07-2011, 03:51 PM
Theory with no real world experience to back it versus reality based testing and 1000's of happy customers who have no complaints, tough decision.

It is not theory. You cannot put a large pin in a small hole. Pin and hole size are determined by numbers on a drawing. If a bullet can be up to X, you should not make the hole X - 0.001 unless you are seeking an interference fit.

As for thousands of customers - the large companies, with millions of combined customers, do it the way I am suggesting. Colt, FN, HK, Sig, Remington, Ruger - they all make the hole larger than the largest in-spec bullet.

rsilvers
08-07-2011, 03:55 PM
Do you have any credible evidence this has ever actually occurred in the real world? Yes or no?

If you are simply asking if bullets sometimes get stuck in chambers, then sure. It happened to me with a 300 Fireball barrel. If you are asking if a bullet has ever been stuck in a 6.8 chamber that had a 0.2770 or 0.2775 diameter throat - I have no evidence of that - but it is smaller than the largest in-spec bullet so why make the hole smaller, on purpose, than what you know a bullet is allowed to be?

I know why - to try to gain accuracy while taking an educated risk at reliability. Palma shooters do it all the time. It is smart if you want to try to win the competition.

For a combat-style rifle, the Bison SPC-II chamber, with reamers actually ordered +0.0015 seems perfect.

Simple Man
08-07-2011, 03:59 PM
I quit reading after this, LOL.

+1 Maybe he should not worry about us and our cartridge and worry about sales of the 300AAC's.Seems like lots of wasted energy on his part.

sfsmedic
08-07-2011, 04:47 PM
We aren't asking vague large pin in small hole questions as you usually reply after your theoretical data with no backing. We are asking directly related to the 6.8 as you have previously eluded was a problem. An eluded problem that no one running these focused specialized products have ever complained about. Versus a company with millions of mass produced product that adds extra tolerances for the just in case episode that again hasn't happened. We call that playing to the lowest common denominator.


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rsilvers
08-07-2011, 04:51 PM
There is no extra tolerance in the SAAMI 6.8 spec.

The bullet may be up to 0.2780, and the throat may be down to 0.2781

That is only a 0.0001 difference.

You can overlap them if you want taking a calculated risk that few 6.8 bullets are actually over 0.2775, but it will raise pressures just like the 223 Wylde chamber - it looks like somewhere in the neighborhood of 2000 psi.

constructor
08-07-2011, 05:30 PM
Here is a post from Art in 06 related to all of this and the chambers, addresses the neck diameter issue and the 45 degree cone angle issue but not the leade diameter that Silvers brought up.

kalwasart [Member]
7/5/2006 12:40:10 PM MDT

Randall, check your 6.8 reamer drawing, at the 45 degree angle at the .2781 lead, is it 1.70185? I have received several drawings from different gun manufactures that have that same dimension. But from another gun manufacture I have 1.7109 which I believe is the correct dimension.

If the 1.70185 is being used that means the 45 degree angle can not exist and you will end up with a sharp corner at the lead into the chamber. The X-Treme combat loads needs this angle otherwise pressure will peak.

I have a 5 inch thick file on testing on the 6.8 and have to come to the following:

1. Neck size does not have anything to do with increasing pressure and I have the computerize test result to prove it.
2. Cartridges has to be made to the low end of the spec with regards to dimensions.
3. Recently found errors in chamber reamer drawings developed a sharp corner leading into the chamber, which is effecting the X-Treme combat loads. In the June issue of SWAT the Combat X-Treme had excellent results out prefoming all others rounds. You can blame the X-treme all you want but it works in some guns and not in others, so you decide, is it the ammo or the weapon? We however made adjustments to the X-treme to work in weapons with chamber issues.
3,. If your weapon can not shoot projectiles at 2,650 FPS than you have a weapons problem.
4. Some guns have very bad timing problems, where the bolt is trying to open while still under high pressure. Cases ejecting from the 1 to 3 o'clock position. The hotter the load the bigger the problem becomes.
5. If the case are blowing primers and expanding above .424 (being max chamber SAAMI) this is direct result of the bolt opening early.

Our triple Shock thru a Barrett and CMMG is getting 2,715 FPS, can your gun handle it?

The Military has tested the X-Treme at velocities of 2,625 FPS and had no problems. But again who's weapon did they test it in.

We have made changes to the X-Treme so it will work with all weapons, mainly down loading it. We are try to offer a good round at a reasonable price unless everyone wants to shoot just the expensive stuff.

If I was a gun manufacture I would be asking myself if a round is working in someone else gun why is it not working in mine? Or the quick answer is Blame the AMMO.



Art - SSA

sneedb82
08-07-2011, 07:35 PM
Robert,
Question my man. Of all the bullets on the shelf today for a reloader, which ones have been shown to be on the further end of the size spectrum?

Reason I ask, is the commercial products that are available and are being shot seems to be quite miniscule. I mean, the probability of any of us getting one of these projectiles is quite small. The bullets that I'm certain that you're referring to that there's a chance for getting stuck in the smaller SPCII chambers are made for .270WIN anyway... So we're talking about larger weight projectiles that are being loaded in bolts or single shot rifles. Am I mistaken here?

I'm not trying to take sides here at all... however, I'm trying to be logical in terms of 6.8SPC, and SPCII. I'm sure the above questions can be addressed further with HTR, BWilson, and H offering their professional and expert experience also.

I'm a consumer. Not a professional. And I rely on the professionals to make certain QC is top notch, before I start buying a product. I don't reload/handload... unfortunately, I'm one of those consumers that has to wait until a certain projectile comes out, or find a good friend to load for me. So this is very important to me in terms of reality and feasibility.

rsilvers
08-07-2011, 07:52 PM
I don't know which bullets tend to be the largest in 6.8.

Aside from that, I ask that you consider leaving room for runout (bullets that are not in straight - as most are but to varying degrees), as this will cause rub even for bullets that are 0.2770.

http://www.sinclairintl.com/.aspx/pid=37479/Product/Sinclair_Concentricity_Gage
(http://www.sinclairintl.com/.aspx/pid=37479/Product/Sinclair_Concentricity_Gage)
Also it makes it harder for ammo to drop into and out of a chamber gauge made to that drawing - which would only be a problem if the 0.2770 or 0.2775 were to become a new standard.

I am not arguing for a sloppy chamber - just sayin' that the 0.2781 of the SAAMI chamber was already aggressively snug and smaller raises pressure.

WVHunter1s1k
08-07-2011, 08:19 PM
+1 Maybe he should not worry about us and our cartridge and worry about sales of the 300AAC's.Seems like lots of wasted energy on his part.

Good one!!

sfsmedic
08-07-2011, 08:41 PM
+1 Maybe he should not worry about us and our cartridge and worry about sales of the 300AAC's.Seems like lots of wasted energy on his part.

I've made my product as good as reasonably expected what can I do now? Oh I know, disparage my biggest threat.

That is the type of behavior that I've ever seen from this gentlemen. I can honestly say I've never seen anything in the form of contribution on this forum from this individual. Only theoretical and opinion based disparaging remarks about the round and chamber.


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constructor
08-07-2011, 09:19 PM
I kind of like when he brings things up, we've had 14 sales today since this thread started.

nemohunter
08-07-2011, 09:34 PM
I kind hope one of those was Zack's barrel.

John A.
08-07-2011, 10:11 PM
From this thread



This is not something that is a debate or opinion, just a fact. As you can see in this drawing, bullets may be up to 0.278:



I don't know which bullets tend to be the largest in 6.8.

And on other forums
http://www.xdtalk.com/forums/ar-talk/178987-weighing-my-options-one-6-5-6-8-aac-300-a.html#post2932350

Yeah, those are pretty good numbers. Or at least better than some I have been hearing. But at the same time, if it maxes out at 2400, then the numbers are only going to go down as the bullets get heavier.

To keep things in perspective, the 110 gr 6.8 Hornady vmax get about 2635 fps average, so only a couple hundred fps advantage there. And likely due to pushing a smaller diameter bullet.


Not true. It is 2540 fps for the Hornady 110 V-MAX in 6.8.

Hornady : Law Enforcement | Products | 6.8MM SPC - 6.8MM SPC 110gr. V-MAX™ (http://www.hornadyle.com/products/more_detail0b05.html?id=72&sID=151&pID=2)



This is a recent post from one of the moderators at 68forum. I do not know the specifics of the barrel he was using (lenght/twist/rifling) but he has never given me a reason to doubt his credibility before.

Post #109 http://68forums.com/forums/showthread.php?21712-New-6.8-ammunition-4-sale-!!!-Great-pricing/page11 (http://68forums.com/forums/showthread.php?21712-New-6.8-ammunition-4-sale-!!!-Great-pricing/page11)



I am going to go with Hornady's test-barrel data over data from an individual's rifle both because the chamber is verified, the bore is verified to meet SAAMI specs, and their chronograph is probably calibrated. If you shoot from a tight chamber or bore, then you will have more velocity.

The 300 AAC BLACKOUT 123 grain which we rated at 2315 fps was getting 2360 fps in individual guns, but we still called it 2315.


As for ammo - there are a couple of things to mention. First, on supersonic - that is being redesigned. So there is no supersonic ammo shipping now. The new round will be UMC and an open tip match. It should be awesome. Even before that ships, we will ship a high-end Premiere Match 125 grain. That has already been shipping to certain customers, but will be shipping to everyone in Aug.

Subsonic - that is shipping every few weeks in large quantities. This is the lowest price I have seen so far:

76290 - Ammo 300 AAC Blackout OTM 220 Grain Subsonic 20 Round Box (http://www.cheaperthandirt.com/76290-1.html)

and from:

https://snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2339681&page=all


Originally Posted By: bustin
The ballistics aren't close to the 6.8. 200fps is the difference between a standard and Magnum.
300aac 123gr bullet 2300fps
6.8 120gr 2500 factory , 2600 handloaded both out of 16" barrels, 110gr bullet factory 2600fps, handloaded 2750.


Sigh. That is simply not true.

http://www.hornadyle.com/products/more_detail0a5d.html?id=72&sID=151&pID=1 (http://www.hornadyle.com/products/more_detail0a5d.html?id=72&sID=151&pID=1)
http://www.hornadyle.com/products/more_detail0b05.html?id=72&sID=151&pID=2 (http://www.hornadyle.com/products/more_detail0b05.html?id=72&sID=151&pID=2)

6.8 SPC 110 gain is 2443 fps from a 16 inch barrel. 2540 fps for a V-MAX.

300 AAC BLACKOUT is 2450 fps for a 110 grain from a 16 inch barrel at the 55,000 psi SAAMI pressure limit.

So 300 BLK is 1466 ft-lbs for 110 grain while 6.8 SPC is 1458 ft-lbs or 1576 for V-MAX.

6.8 is only 7% more powerful from a 16 inch barrel, and is actually less powerful from very short barrels.



You can sigh all you want slivers but i have 6.8s in my hand about 14hrs a day and know more about what they are capable than you ever will, you still think a 8 twist barrel is the best thing for a 6.8? You and Remington may only be able to get those velocities out of a 6.8 because you guys messed up the throat and use large primers but the rest of the world is getting much better performance from the 6.8.
Come on over to colorado and I'll show you 2800fps out of a 16" 6.8, then I want to give you the exact same load to shoot in your Remington 6.8, but you'll need to pull the trigger on yours.
Hype your **** all you want but I know the truth.
A full length 5.56 case has 28.5gr H2O capacity, the 6.8 has 36gr capacity but you think they achieve the same velocity at the same pressure? Didn't you tell me you had to load the 300AAC bullets short so they don't hit the front rib in a 5.56 case and that very detailed instructions would be included for those that handload? Remember I posted a photo where someone in you organization had loaded a 300 with the bullet out at 2.25" which filled a Magpul mag but was hitting that front rib, it was in an advertisment? So after you set the bullet deeper in a case that has less capacity to start with how do you get more velocity especially with an 8 twist barrel?
A major plus of the 300aac was that it could use 5.56 mags but this thread on arfcom makes it sound like loading short will not work and special 300AAC mags must be used or the rib in the mags must be filed down go to 2nd page-- special mag thread (http://www.ar15.com/forums/topic.html?b=3&f=121&t=525730&page=2) . So loading short in order to miss the front mag rib preventing binding in a 5.56 mag wasn't taken into account when the chamber was designed with a long throat and now you can't load short to use 5.56 mags because the accuracy suffers due to the long throat and the mags allow the cartridge to nose dive stuffing the bullet tip into the receiver and now you must make special mags without the front rib? There goes the plus but, at least you can still use 5.56 bolts.
I didn't say there was anything wrong with what the 300 does or will do before but trying to make other cartridges look bad to make your own look better is deceiving to customers and they will find out the truth eventually. Got to be careful when you stir ****, you may splash some.
Just to jog your memory-

Originally Posted by rsilvers
We figured that out - though shooting thousands of rounds. We started with 60,000 rounds and most of that is gone.

The OAL of the shipping ammo is shorter than in that photo and set up so that the ammo is not cocked off center by the rib in a USGI magazine. In the 'owner's manual' (downloadable form the website) I list the recommended OAL for a number of popular bullets. None of them are over 2.1 inches OAL.

My concern is that when ammo companies start to load ammo they will make mistakes of that kind and it will cause user frustration. That is why I did not keep that knowledge a secret and put it in the documents. I want the cartridge to be a success, and part of that is heading off such problems.


And from:
http://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/4889472/Re_300_ACC_Blackout


The throat is about 0.050 longer than in a 300-Fireball wildcat. That is about the same difference as the throat in the 6.8 SPC-II chamber vs the SAAMI 6.8 chamber.


You have went around just about every gun forum in the country trying to push the blackout and talk down all the competing rounds on assumptions and theories and half truths.

Just because a lot of people who visit a gun forum may not know all the little details, but there are many who can see through what you're trying to do, and you aren't doing yourself any favors.

Moderators, if this means you should throw the ban hammer at me, then so be it, but this guy is turning into his own cheering section.

sneedb82
08-07-2011, 10:13 PM
I don't know which bullets tend to be the largest in 6.8.

Aside from that, I ask that you consider leaving room for runout (bullets that are not in straight - as most are but to varying degrees), as this will cause rub even for bullets that are 0.2770.

http://www.sinclairintl.com/.aspx/pid=37479/Product/Sinclair_Concentricity_Gage
(http://www.sinclairintl.com/.aspx/pid=37479/Product/Sinclair_Concentricity_Gage)
Also it makes it harder for ammo to drop into and out of a chamber gauge made to that drawing - which would only be a problem if the 0.2770 or 0.2775 were to become a new standard.

I am not arguing for a sloppy chamber - just sayin' that the 0.2781 of the SAAMI chamber was already aggressively snug and smaller raises pressure.


I'll try and sum this up in layman's terms then, Robert.

What you're saying is the attempt to change the SAAMI chamber to what we currently have, in either the MOD1 from Noveske, or the x43 and DMR chambers is futile, as it does not do anything more relevant than the original SAAMI specs?

Anyone want to test a 1/11" twist SAAMI barrel with some handloaded or SSA tactical loads and let me know how well that works out? I'm not trying to be a relative to the horse's backside here, but I think that the companies whom invested a lot of money into the new x43 chambers have made almost if not all of their initial investment back, and the only issue to date that I've seen or heard of on the interwebs about any issues, were out of spec bolts with the wrong barrels, and various other QC issues. The chambers I hadn't heard of any.

I don't know where else the intent is going here other than trying, for some sort of financial gain for your parent company, to eliminate the efforts of the 6.8 community to resubmit or seek for a change in the SAAMI specs originally sent from Remington. Am I incorrect in stating that?

rsilvers
08-07-2011, 10:29 PM
I'll try and sum this up in layman's terms then, Robert.

What you're saying is the attempt to change the SAAMI chamber to what we currently have, in either the MOD1 from Noveske, or the x43 and DMR chambers is futile, as it does not do anything more relevant than the original SAAMI specs?

I am unfamliar with Noveske's chamber.

In practical terms, what I am saying is that the 6.8 SPC-II "Bison" chamber will have about 1500 psi less pressure than the SAAMI chamber, but the DMR and 6.8x43 would not be expected to have less pressure than a SAAMI chamber. And if that is contrary to what you have seen in the real world, it is because of other factors - such as larger bores, or reamers ordered larger than the values actually on the drawing.


I don't know where else the intent is going here other than trying, for some sort of financial gain for your parent company, to eliminate the efforts of the 6.8 community to resubmit or seek for a change in the SAAMI specs originally sent from Remington. Am I incorrect in stating that?

No, because I am recommending the 6.8 SPC-II Bison chamber for new rifles. That is the one which should be submitted as a new standard if one were to decide to submit a new standard.

sneedb82
08-07-2011, 10:49 PM
Thanks for the clarification.

morts10
08-07-2011, 11:00 PM
So the reason I cannot find any supersonic ammo for my weapon is because it has to be redesigned?? I keep going to my local gunshop and while I can find about 5 or 6 types of ammo for my 6.8 I can only find one kind of ammo for my 300 and its all sub. I thought all the bugs were ironed out before release. I would think it would be wise on your part to spend more time on the 300aac real world problems and less time worrying about the theoretical problems with the 6.8 specll.

Just my .02s


mort

rsilvers
08-07-2011, 11:11 PM
There are two types of supersonic ammo coming out within a few weeks. Match and AccuTip. The low-cost ammo is being redesigned and won't be out until Oct/Nov. And after that, CoreLokt.

constructor
08-07-2011, 11:23 PM
I am unfamliar with Noveske's chamber.

In practical terms, what I am saying is that the 6.8 SPC-II "Bison" chamber will have about 1500 psi less pressure than the SAAMI chamber, but the DMR and 6.8x43 would not be expected to have less pressure than a SAAMI chamber. And if that is contrary to what you have seen in the real world, it is because of other factors - such as larger bores, or reamers ordered larger than the values actually on the drawing.



No, because I am recommending the 6.8 SPC-II Bison chamber for new rifles. That is the one which should be submitted as a new standard if one were to decide to submit a new standard.
The chamber I use is my chamber, mine. I use it in the rifles I build to give our customers the best accuracy and performance I possibly can.
Has anyone ever said my chamber was going to be submitted? NO they haven't so what are you yakking about?
As I said before, you are coming in late, don't know many details at all and are assuming a lot considering you have very very little experience with the 6.8.
Art at SSA designed the SPCII chamber, Kotonics may have been the first company to use it in any quantity in 2006, LWRC and Barrett adopted it quite a while back sometime in 2006 and now most in the industry are using it. Bison didn't design it but they did start using it in 2009, Wilson Combat has been using it since they got involved a few years ago. Almost every manufacturer except 3 I think is using the SPCII chamber and as far as I know none of them want to pay to have SAAMI approve it.

You don't have a clue what 6.8x43 chamber specs were sent to doc yet you don't think it should be used... huh? I don't think Doc ever sent anything to anyone.
When Tim and I talked we wanted to get rid of the Remington name since they dropped support of the cartridge so we dropped it from the reamer prints.
LWRC had barrels marked 6.8x43 Nato at least 2 years ago, what were the specs on those chambers that you don't think should be used Sliver?
If you really think my 6.8x43 will not shoot any hotter loads than a SAAMI chamber bring your SAAMI chambered rifles out and shoot 33gr of H335 behind a 115gr bullet like I do in these barrels we sell. I hate to tell you but I am not changing my chamber because of your inexperienced views on anything. Just to really throw you off we also sell a barrel with a SPCII chamber.
The military isn't looking at the 6.8 so what does it matter? Or are you just trying to cast a shadow of doubt hoping your 300 will take off?
If they were looking at the 6.8 I would think like all things they will develop their own chamber, just like the 5.56 and 7.62 nato.

rsilvers
08-07-2011, 11:30 PM
If you really think my 6.8x43 will not shoot any hotter loads than a SAAMI chamber bring your SAAMI chambered rifles out and shoot 33gr of H335 behind a 115gr bullet like I do in these barrels we sell.

As I have tried to explain to you, that would not be a valid test, because the bores would not have the same cross-sectional area. Further, your chambers may use reamers made to 0.0015 larger than the drawing. Do they?

sfsmedic
08-07-2011, 11:32 PM
I kind of like when he brings things up, we've had 14 sales today since this thread started.

+1!!!


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sfsmedic
08-07-2011, 11:35 PM
As I have tried to explain to you, that would not be a valid test, because the bores would not have the same cross-sectional area. Further, your chambers may use reamers made to 0.0015 larger than the drawing. Do they?

There is a point lab testing goes bu-bye and off the shelf destructive testing takes over. We grab your rifle off the shelf with your chamber and load to destruction than do it again with a production ARP rifle. Viola market destructive testing. Bet his goes further.

Sounds pretty productive to me. What do you think H?


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rsilvers
08-07-2011, 11:39 PM
If he opens the throat diameter an extra 0.001 the pressure will drop even more.

sfsmedic
08-07-2011, 11:41 PM
And again since there hasn't been any issues with his current chamber then why change it? Don't fix what ain't broke. That's hillbilly theoretical testing right there!



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WVHunter1s1k
08-07-2011, 11:42 PM
Originally Posted by rsilvers Sigh. That is simply not true.

http://www.hornadyle.com/products/more_detail0a5d.html?id=72&sID=151&pID=1 (http://www.hornadyle.com/products/more_detail0a5d.html?id=72&sID=151&pID=1)
http://www.hornadyle.com/products/more_detail0b05.html?id=72&sID=151&pID=2 (http://www.hornadyle.com/products/more_detail0b05.html?id=72&sID=151&pID=2)

6.8 SPC 110 gain is 2443 fps from a 16 inch barrel. 2540 fps for a V-MAX.

300 AAC BLACKOUT is 2450 fps for a 110 grain from a 16 inch barrel at the 55,000 psi SAAMI pressure limit.

So 300 BLK is 1466 ft-lbs for 110 grain while 6.8 SPC is 1458 ft-lbs or 1576 for V-MAX.

6.8 is only 7% more powerful from a 16 inch barrel, and is actually less powerful from very short barrels.

http://shopwilsoncombat.com/68-SPC/products/409/

Use slow cartridges eh. Nice trick BuB!!
110gr = 2450fps. What a slug!

Oh, wait... they can't be shot with SAAMI Spec barrels. Darn!! I guess you all will have to take your SAAMI rifles & go home.

Too bad Remington can't man/Cowboy up admit they made a mistake, make it right & move on.


Originally Posted by constructor If you really think my 6.8x43 will not shoot any hotter loads than a SAAMI chamber bring your SAAMI chambered rifles out and shoot 33gr of H335 behind a 115gr bullet like I do in these barrels we sell.

As I have tried to explain to you, that would not be a valid test, because the bores would not have the same cross-sectional area. Further, your chambers may use reamers made to 0.0015 larger than the drawing. Do they?

Action talks. BS Walks. The gauntlet has been tossed.

rsilvers
08-07-2011, 11:43 PM
And again since there hasn't been any issues with his current chamber then why change it? Don't fix what ain't broke. That's hillbilly theoretical testing right there!

You don't need to change it. If the goal is to reduce pressure, then adding 0.001 will do that.

What I am saying is simple - the 6.8 SPC-II chamber has about 1500 psi less pressure than 6.8 SAAMI.

And SAAMI and 6.8x43 are a wash - both with more pressure than 6.8 SPC-II.

constructor
08-07-2011, 11:47 PM
Hornady and SSA 110gr loads are both reaching right at 2600 out of our 16" barrels at 4500ft elev.
2450fps is what I was getting in 2005 with a SAAMI chamber and 9.5 twist barrel and the primers were either flat are blown at 9800ft elev.

sfsmedic
08-07-2011, 11:48 PM
Obviously you do because the guys here who have spent countless hours real world testing have produced a different chamber capable of more than the saami SPC chamber ever allowed. Your tests that prove otherwise always keep one of the most important variables constant (the bullet) which actually makes the test null and void because what the chamber does is allow hotter bullets that reach more fps. You test different chambers with the same bullet expecting to get no gain which is what you get. Now change that variable and you will get the fps we are discussing which is safe in the SPC II and 6.8x43 chamber that isn't safe in the SPC chamber. Again the tests are only as strong as the data and your data sir is skewed and weak. I guarantee your response will be what it is on countless other threads this comes up on, flawed and missing the point of why a hotter round to test, because saami says yadda yadda.


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constructor
08-07-2011, 11:56 PM
You don't need to change it. If the goal is to reduce pressure, then adding 0.001 will do that.
The only time you will see a pressure rise is if the bullet is larger than the throat if it is not touching as in the case of the 6.8 it does not raise the pressure.
The Border barrel test was testing extreme examples of a match barrel like a Krieger tightbore 307/.298 where a normal 308 barrel has a .308 groove and .300 bore.
The bullets used were a full .308 diameter.001 larger than the throat, Lapuas 308 bullets are known to be .3075 and shoot better in the tight bore Kriegers.

rsilvers
08-07-2011, 11:59 PM
Obviously you do because the guys here who have spent countless hours real world testing have produced a different chamber capable of more than the saami SPC chamber ever allowed.

Differences in pressure and velocity are also effected by the bore, headspace, and if the chamber is made to SAAMI min or SAAMI max.

When the 6.8x43 chamber added additional lead, the pressure dropped. When it went to a smaller diameter freebore, the pressure goes back up. The two effects work to cancel each other out.

Constructor - do you order your 6.8x43 reamers to the drawing or about 0.0015 larger than the values on the drawing?

sfsmedic
08-08-2011, 12:01 AM
Probing the witness, I object. Lmao.


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rsilvers
08-08-2011, 12:05 AM
The only time you will see a pressure rise is if the bullet is larger than the throat if it is not touching as in the case of the 6.8 it does not raise the pressure. ...The bullets used were a full .308 diameter.001 larger than the throat, Lapuas 308 bullets are known to be .3075 and shoot better in the tight bore Kriegers.

That is incorrect. The test used a 0.3100 and a 0.3085 throat - both were larger than the bullet, which was 0.308. Anyone can check this as I gave the link - but to make it easier, here is a marked-up graphic from the document:

http://img708.imageshack.us/img708/8202/pressure.png

Also, I just put some Lapua bullets on a micrometer, and they read 0.30800 to 0.30810.

constructor
08-08-2011, 12:10 AM
As I have tried to explain to you, that would not be a valid test, because the bores would not have the same cross-sectional area. Further, your chambers may use reamers made to 0.0015 larger than the drawing. Do they?
No, that would be out of tolerance of the reamer spec.
So you are yakking about a .0005 difference in the 2 chambers? That is 5 ten thou., 1/2 of 1 thou or 1/8th as thick as a piece of paper. So how thick is chrome that would be used in the military barrels? times 2 for each side so what is the diameter after chrome?
Also you are promoting a stainless barrel which we know the military will not accept. You said on M4.com that many consumers really do want a combat grade weapon yet you advise them to buy a stainless barrel that may last half as long as a 4150 Melonite treated barrel? hmmm interesting choice. Do YOU want a stainless barrel for a combat grade weapon?

rsilvers
08-08-2011, 12:15 AM
I don't remember recommending a stainless barrel. Please show where I said that. I would rather have a nitrided carbon steel barrel.

Chrome-lined barrels are made oversize to account for the chrome. If you don't have the tooling oversized, you can electropolish it.

John A.
08-08-2011, 12:21 AM
If you really think my 6.8x43 will not shoot any hotter loads than a SAAMI chamber bring your SAAMI chambered rifles out and shoot 33gr of H335 behind a 115gr bullet like I do in these barrels we sell.


As I have tried to explain to you, that would not be a valid test, because the bores would not have the same cross-sectional area. Further, your chambers may use reamers made to 0.0015 larger than the drawing. Do they?

Sounds valid enough to me.

I've heard over and over from you how wrong and inferior the 6.8 is based on outdated data and collected on parts that have since been improved upon.

Sure, Saami doesn't recognize SPCII or whatever chamber because nobody has taken the time or money to submit it to them to my knowlege.

Not because it's not a better mousetrap.

Repeatedly, I have seen several people challenge you (errr Remington or whoever) to put up or shut up. It's really that simple. I really wish you would pick one or the other instead of chalking up how awesome the blackout is, even though the experimentation and other subsequent work was already done by JD Jones by way of the Whisper, but submitted to Saami with enough minor changes to argue in court for saami to say "This is the 300 AAC Blackout".

Even in grade school, copying was against the rules. Just because you put a comma in a different place than JD, still doesn't change what you did.

constructor
08-08-2011, 12:28 AM
That is incorrect. The test used a 0.3100 and a 0.3085 throat - both were larger than the bullet, which was 0.308. Anyone can check this as I gave the link.

Also, I just put some Lapua bullets on a micrometer, and they read 0.30800 to 0.30810.
The chart I saw was a .307 bore that raised pressure 200-250 bar.
Anyone in the benchrest community can tell you Lapua bullets have run undersize for years, that is one reason the PacNor barrel shoot them so well because Pac Nor barrels are slightly undersized. A main reason Kreiger makes .298 bore Plama barrel is because of the Lapua palma bullets. I have 2 both 13 twist and shoot 155gr Scenars and have for years. I know you will **** about that 13 twist in a 308 so why don't you go over to 6mmBr.com and try to get all of those guys shooting Palma matches to change to that 8 twist that you think is perfect for everything.

Barrels with a bore dimension of .298" and a groove dimension of .3065 are typical of a large number, if not the majority, of barrels used in the sport of Fullbore Target Rifle shooting. Most of these barrels have throat diameters of .3085" or less. Commercially available, C.I.P. approved ammunition could be potentially dangerous in rifles with tight throat and barrel dimensions.


In general, the results behave as expected in that the pressure does increase as the throat and barrel dimensions decrease. The increase in pressures due to barrel dimensions alone is relatively modest - around 200 to 250 bar for each .001" that the barrel dimensions are reduced. This represents a 5% increase in pressure for a 0.3% decrease in barrel diameter. It is interesting to note the sensitivity of pressure to the throat diameter though, particularly when the throat diameter is smaller than the bullet diameter and the bullet is an interference fit into the throat.

SixEight
08-08-2011, 12:43 AM
I'm just glad nobody is spending freakishly obsessive amounts of time trying to discredit the 7.62x39 lite or if you prefer 300 whisper 2.0. That would just be mean.

constructor
08-08-2011, 12:48 AM
I don't remember recommending a stainless barrel. Please show where I said that. I would rather have a nitrided carbon steel barrel.

Chrome-lined barrels are made oversize to account for the chrome. If you don't have the tooling oversized, you can electropolish it.
You are recommending Bison barrels, they are all stainless or did you notice?
We aren't talking about the barrel bore dia, you were talking about a specific reamer that had a .278 throat, so are you saying now you don't really want a "Bison" chamber with a .278 throat but a .279 throat to take care of the added chrome?

rsilvers
08-08-2011, 12:55 AM
In general, the results behave as expected in that the pressure does increase as the throat and barrel dimensions decrease. The increase in pressures due to barrel dimensions alone is relatively modest - around 200 to 250 bar for each .001" that the barrel dimensions are reduced.

Agreed. Now convert that to psi:

200 bar = 2900 psi.
250 bar = 3626 psi.

rsilvers
08-08-2011, 12:56 AM
You are recommending Bison barrels, they are all stainless or did you notice?

I never recommended a Bison barrel.

rsilvers
08-08-2011, 01:00 AM
...so are you saying now you don't really want a "Bison" chamber with a .278 throat but a .279 throat to take care of the added chrome?

I am saying that I want the freebore diameter to be no less than 0.2781. If it is a chromed barrel, then I would want this 0.2781 to be after chrome of course.

constructor
08-08-2011, 01:08 AM
Agreed. Now convert that to psi:

200 bar = 2900 psi.
250 bar = 3626 psi.
Yeah I know how to convert. Is it time for our secret squirrel handshake?

http://en.wikipedia.org/wiki/Straw_man

I hate to tell you but in the end our $200 barrels with that screwed up chamber still shoots the hottest loads and 3/8" groups and it just bothers me to no end.
I can't sleep at night thinking about how I could have made such a mistake.

rsilvers
08-08-2011, 01:12 AM
Having a tight throat is well known to help accuracy, of course, that is why you do it. And that is why Palma shooters do it.

sfsmedic
08-08-2011, 01:33 AM
Having a tight throat is well known to help

too easy. See what out of context can do to you? Like alot of the data you elude too


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angsniper
08-08-2011, 09:19 AM
Yeah I know how to convert. Is it time for our secret squirrel handshake?

http://en.wikipedia.org/wiki/Straw_man

I hate to tell you but in the end our $200 barrels with that screwed up chamber still shoots the hottest loads and 3/8" groups and it just bothers me to no end.
I can't sleep at night thinking about how I could have made such a mistake.

http://www.freesmileys.org/smileys/smiley-laughing001.gif (http://www.freesmileys.org/smileys.php)http://www.freesmileys.org/smileys/smiley-laughing025.gif (http://www.freesmileys.org/smileys.php)http://www.freesmileys.org/smileys/smiley-laughing024.gif (http://www.freesmileys.org/smileys.php)

Force
08-08-2011, 09:35 AM
Yeah I know how to convert. Is it time for our secret squirrel handshake?

http://en.wikipedia.org/wiki/Straw_man

I hate to tell you but in the end our $200 barrels with that screwed up chamber still shoots the hottest loads and 3/8" groups and it just bothers me to no end.
I can't sleep at night thinking about how I could have made such a mistake.

Classic !
I read all 7 pages of this last night. Couldn't stop.
It was all I could do to not post some rather choice comments.

H, something must be wrong with my 6.8 x 43 barrel !
It will shoot the hottest loads, groups around 3/8 " and continues to do so.
Clean, caked with mud and sand. Even half frozen !
Shoots whatever loads I put in it.

Keep up the good work !

rsilvers
08-08-2011, 09:57 AM
You should not shoot 6.8 SPC-II loads in a 6.8x43 chamber anymore than you should in a SAAMI chamber because both have smaller dimensions than 6.8 SPC-II. Either you can in neither or you can in both.

68WJ
08-08-2011, 11:06 AM
You should not shoot 6.8 SPC-II loads in a 6.8x43 chamber anymore than you should in a SAAMI chamber because both have smaller dimensions than 6.8 SPC-II. Either you can in neither or you can in both.
Maybe in some abstract, theoritical world, but reality has proven too many times this is not a problem. There are many users who own one of H's barrels and another with SPCII. I know that you will credit bore cross-section for this phenomenon, but they successfully shoot SPCII loads in the x43 chamber.

Some have even seen the reverse as being the problem, that max loads for the x43 show increased pressure in their SPCII.

constructor
08-08-2011, 11:22 AM
You should not shoot 6.8 SPC-II loads in a 6.8x43 chamber anymore than you should in a SAAMI chamber because both have smaller dimensions than 6.8 SPC-II. Either you can in neither or you can in both.
You really should stop smoking that **** The more you talk about stuff that you know nothing about the worse you look.
We and I mean thousands of customers have been shooting the hottest loads out of these barrels with the chambers I have designed since 2007.
The 85gr TSX has been shot to 3170fps, the 115gr to 2800fps out of 16" barrels, that is close to 200fps faster than any factory load.
I and everyone here know what we can shoot in these barrels because we have experience in shooting them, something you know nothing about
You aren't going to convince people that have done it and seen it with their own eyes.
Now if you want to go design a button and a reamer and have some barrels made with your 8 twist barrel and SAAMI chamber and shoot that and mine side by side to see the results lets do it. Put your money where your mouth is and we'll meet in Texas at HTR's ranch and shoot them, you can prove us wrong.

marinesg1012
08-08-2011, 11:27 AM
You should not shoot 6.8 SPC-II loads in a 6.8x43 chamber anymore than you should in a SAAMI chamber because both have smaller dimensions than 6.8 SPC-II. Either you can in neither or you can in both.

This is ridiculous, I have two of Harrisons uppers one with the DMR and another with the DMR-C (designed for use with chrome) both of those will shoot handloads that I would never suggest people here use unless they work up to them.

Sorry but I dont know what your smoking but the info you post on the 68 is simply not true.

rsilvers
08-08-2011, 11:37 AM
Maybe in some abstract, theoritical world, but reality has proven too many times this is not a problem. There are many users who own one of H's barrels and another with SPCII. I know that you will credit bore cross-section for this phenomenon, but they successfully shoot SPCII loads in the x43 chamber.

Sure. That makes sense, since I only expect it is raising pressure about 2000 psi compared to a 6.8 SPC-II chamber and barrel which is otherwise identical except for the throat diameter. But I would also expect that you could take that same barrel and turn off the back and re-chamber it with a SAAMI reamer and also have no problem - as the SAAMi chamber compared to SPC-II is about 1500 psi. Art from SSA has plenty of old 6.8 rifles which handle the pressure of his hotter ammo.

rsilvers
08-08-2011, 11:39 AM
This is ridiculous, I have two of Harrisons uppers one with the DMR and another with the DMR-C (designed for use with chrome) both of those will shoot handloads that I would never suggest people here use unless they work up to them.

Sorry but I dont know what your smoking but the info you post on the 68 is simply not true.

What I said is exactly true. I think you are reading something other than what I wrote. I did not say that Harrison's rifles could not shoot hot loads! I said that whatever a 6.8x43 chamber could handle, so could a SAAMI chamber - as they both raise pressures over 6.8 SPC-II chambers.

sfsmedic
08-08-2011, 11:42 AM
So for the 100th time. Break out your saami chamber and let's start working up loads and see whose fails first? Money, mouth.


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rsilvers
08-08-2011, 11:43 AM
Now if you want to go design a button and a reamer and have some barrels made with your 8 twist barrel and SAAMI chamber and shoot that and mine side by side to see the results lets do it. Put your money where your mouth is and we'll meet in Texas at HTR's ranch and shoot them, you can prove us wrong.

The test is easier than that. Just take two sequentially-made blanks and chamber one with DMR or 6.8x43, and the other in SAAMI. Headspace them the same. The SAAMI will take as much pressure as the others.

The reason your rifles handle pressure is going to be due to the bore.

rsilvers
08-08-2011, 11:44 AM
So for the 100th time. Break out your saami chamber and let's start working up loads and see whose fails first? Money, mouth.

This is not scientific, but still interesting. Take a new Ruger rifle and see how it handles SSA's current Tactical ammo. Who here thinks it will have a problem? Post if you think it will have a problem.

sfsmedic
08-08-2011, 11:47 AM
How does factory ammo equate to "working up loads" in your mind?

Btw "it's not scientific" as you say but we are making a point of showing your science is flawed.
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marinesg1012
08-08-2011, 11:52 AM
What I said is exactly true. I think you are reading something other than what I wrote. I did not say that Harrison's rifles could not shoot hot loads! I said that whatever a 6.8x43 chamber could handle, so could a SAAMI chamber - as they both raise pressures over 6.8 SPC-II chambers.

Send me a SAMMI barrel and I will take one of my handloads with 30.2 grains of 10X behind a 110 accubond and we will see what happens... in my 1-12 DMR rifle I barely get a swipe.

68WJ
08-08-2011, 12:03 PM
This is not scientific, but still interesting. Take a new Ruger rifle and see how it handles SSA's current Tactical ammo. Who here thinks it will have a problem? Post if you think it will have a problem.
Ever been to the Badlands facility in OK? I hear there will be a great opportunity to stretch out some 6.8's. :a01:

constructor
08-08-2011, 12:11 PM
This is not scientific, but still interesting. Take a new Ruger rifle and see how it handles SSA's current Tactical ammo. Who here thinks it will have a problem? Post if you think it will have a problem.

SSA's new TAC loads are not that fast, not near as fast as their old Combat loads. They were downloaded in 2009 so more rifles could shoot them safely.
I have no idea why since you say any SAAMI chamber can handle them.
The fact is any rifle should handle any factory load just fine now except for the Wilson Combat ammo which is where the old SSA Combat loads were.
People buy the better spec rifles because they can handload to much faster velocities and some barrels actually produce more velocity than other barrels with the same load, it could be because the gas isn't going around the bullet in the larger diameter throat. In the end consumers will choose known end performance, they really don't give a **** why the end result is really the only thing that matters.
The deal is you have no experience with the 6.8... none...zero. I doubt you have ever pulled a trigger on one but you come here and go to other forums to give people advice about what to buy. What makes you think you know enough about the 6.8 to give advice? We all know what your agenda is, you can try here but most here have more experience with the 6.8 than you do, they know what works.

SixEight
08-08-2011, 12:15 PM
Mr. Silvers,
You posted this on m4 back in May with regards to the SAAMI, SPCII, and 6.8x43 chambers.



No major ammo maker makes SPCII ammo.

SAAMI is the standard. The sooner people get over this, the better chance 6.8 has to stop confusing people and grow. But it is best to get one of the other chambers when you buy a rifle.


So correct me if I'm misunderstanding something here but you were recommending SPCII and 6.8x43 interchangeably over SAAMI but now you feel the reverse is true? Is this due to this new information that you've gotten about having found bullets measuring ~0.2780 in diameter or when did the change of heart take place?

rsilvers
08-08-2011, 12:17 PM
Constructor - you had no response to the chart I posted proving you were incorrect about the pressure gain from the throat diameter changes. You have run out of facts so you argue about my experience and agenda. I have a Barrett 6.8 and yes, I have shot it.

It is a fact that the 6.8x43 chamber is smaller than the 6.8 SPC-II chamber. It is a fact that this raises pressure. There is no denying it. I also realize you make up for this with your bore design, so in fact you can shoot hot loads. I am not arguing against that. I was only commending on the chamber differences.

Both 6.8 SAAMI and 6.8x43, if made to the drawing, will both have more pressure than 6.8 SPC-II by a similar amount, all else being equal.

rsilvers
08-08-2011, 12:20 PM
Mr. Silvers,
You posted this on m4 back in May with regards to the SAAMI, SPCII, and 6.8x43 chambers.
So correct me if I'm misunderstanding something here but you were recommending SPCII and 6.8x43 interchangeably over SAAMI but now you feel the reverse is true? Is this due to this new information that you've gotten about having found bullets measuring ~0.2780 in diameter or when did the change of heart take place?

No, I have not found larger bullets.

I recommend that rifles be made with the 6.8 SPC-II chamber while ammo be tested in a SAAMI test barrel.

sfsmedic
08-08-2011, 12:23 PM
Hmm yet no pressure signs from me loading hot. Something must be amiss. I better throw my barrel away as it's possessed by demons because the science says one thing and the real world experience doesn't equate. Witchcraft!!!


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- Sent from my iPhone using Tapatalk

SixEight
08-08-2011, 12:23 PM
No, I have not found larger bullets.

I recommend that rifles be made with the 6.8 SPC-II chamber while ammo be tested in a SAAMI test barrel.

That's not answering the question I asked. Currently, and the cause for this thread is you are saying to go with a SPCII or SAAMI chambered barrel over a 6.8x43 chambered barrel. In the post from May, just the opposite was true. So which is it and why the change of heart?

sfsmedic
08-08-2011, 12:27 PM
He never answers the question. Just vague responses with supposed facts he can never share because they are classified at the G14 scale. I need coffee before I get grouchy.


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- Sent from my iPhone using Tapatalk

Munkie667
08-08-2011, 12:30 PM
Man, this is like a train getting derailed. I can't look away.

sfsmedic
08-08-2011, 12:44 PM
You scared him away Munkie!!


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- Sent from my iPhone using Tapatalk

Munkie667
08-08-2011, 12:45 PM
Damn... Not sure how to fill my morning now. =(

constructor
08-08-2011, 12:47 PM
Constructor - you had no response to the chart I posted proving you were incorrect about the pressure gain from the throat diameter changes. You have run out of facts so you argue about my experience and agenda. I have a Barrett 6.8 and yes, I have shot it.

It is a fact that the 6.8x43 chamber is smaller than the 6.8 SPC-II chamber. It is a fact that this raises pressure. There is no denying it. I also realize you make up for this with your bore design, so in fact you can shoot hot loads. I am not arguing against that. I was only commending on the chamber differences.

Both 6.8 SAAMI and 6.8x43, if made to the drawing, will both have more pressure than 6.8 SPC-II by a similar amount, all else being equal.
If you want the gases produced by the powder to go around the bullet and down the barrel instead of pushing the bullet down the bore faster then just design you a chamber with a big ol sloppy throat. I prefer to get the best accuracy and velocity which seems to be what the customers requirements are. I mean that is the goal of selling stuff right, give the customers what they want not what YOU think they need? Let me ask you, when you design your silencers as you call them are your baffles farther apart than your bullets are long so that the turbulant gases go around the bullet between the baffles and disrupt the bullet flight? I read a paper years ago that said that is where most make their mistake when designing cans. Just curious since you think that is the correct way to design a chamber.

End result man it's the end result,

Keep him busy guys I gotta go machine some stuff.

rsilvers
08-08-2011, 12:52 PM
That's not answering the question I asked. Currently, and the cause for this thread is you are saying to go with a SPCII or SAAMI chambered barrel over a 6.8x43 chambered barrel. In the post from May, just the opposite was true. So which is it and why the change of heart?

I am saying to go with a 6.8 SPC-II, as both SAAMI and 6.8x43 have more pressure (I am not saying to go with SAAMI chamber).

Even in my quote from last May I said to not go with a SAAMI chamber.

SixEight
08-08-2011, 01:01 PM
I am saying to go with a 6.8 SPC-II, as both SAAMI and 6.8x43 have more pressure (I am not saying to go with SAAMI chamber).

Even in my quote from last May I said to not go with a SAAMI chamber.
Yet I refer back to your original post that started this whole damned mess.



I would take a SAAMI chamber such as in the Ruger over an SPCII or 6.8x43 chamber with a 0.2770 or 0.2775 throat.


I don't believe any chamber has a 0.2770 throat so excluding that, you are basically saying you'd take a SAAMI chamber over a 6.8x43 since it HAS a 0.2775 throat. Yet in the other post you say you'd take a SPCII or 6.8x43 over a SAAMI. So it would seem by your current logic, you made a mistake recommending 6.8x43 over SAAMI. The throat AFAIK of the 6.8x43 has always been 0.2775. We aren't talking about a fictitious chamber you would create yourself but currently EXISTING chambers.

TackDriver68
08-08-2011, 01:02 PM
If you are simply asking if bullets sometimes get stuck in chambers, then sure. It happened to me with a 300 Fireball barrel. If you are asking if a bullet has ever been stuck in a 6.8 chamber that had a 0.2770 or 0.2775 diameter throat - I have no evidence of that - but it is smaller than the largest in-spec bullet so why make the hole smaller, on purpose, than what you know a bullet is allowed to be?

I know why - to try to gain accuracy while taking an educated risk at reliability. Palma shooters do it all the time. It is smart if you want to try to win the competition.

For a combat-style rifle, the Bison SPC-II chamber, with reamers actually ordered +0.0015 seems perfect.


-If you are asking if a bullet has ever been stuck in a 6.8 chamber that had a 0.2770 or 0.2775 diameter throat - I have no evidence of that -

So what you're saying is this is another educated(as in 'I was paid to make this up') delusion of 'maybe in the worst case this might happen' . Thanks for the clarification.

Munkie667
08-08-2011, 01:04 PM
It is funny I have put a lot of different rounds through my 6.8x43 from Rem FMJ to Wilson loads and some hotter hand loads. I would have to look at my range book, but I think the total rounds fired from this 6.8x43 is about 1900. And the only problem I have had from time to time was the disconnect ( http://en.wiktionary.org/wiki/disconnect ) between the operator (me) and the trigger. Now I am sure there are other people out there with more rounds down range out of this "inferior" ( http://en.wiktionary.org/wiki/inferior ) chamber. I would love to know how hot a load it was before you started to see pressure signs in a 6.8x43 chamber and the other chambers if you own more then one 6.8.

sfsmedic
08-08-2011, 01:06 PM
-If you are asking if a bullet has ever been stuck in a 6.8 chamber that had a 0.2770 or 0.2775 diameter throat - I have no evidence of that -

So what you're saying is this is another educated(as in 'I was paid to make this up') delusion of 'maybe in the worst case this might happen' . Thanks for the clarification.

Sounds about right. Hmm whats the biggest sloppiest bullet, lets make our chamber to that. LOWEST COMMON DENOMINATOR!
Even though there is no evidence of being a problem we should fix it. Seems we went over this already a few pages ago.

angsniper
08-08-2011, 01:10 PM
Uh, troll. In the military we had what we called a sh!tstick. It was a 5' stick kept in the latrine that was literally used to stir the sh!t so it would flush.

TackDriver68
08-08-2011, 01:17 PM
I think we should turn this thread, along with posts from the other forums into a chart so that this guy's changing and contradictory words can be viewed side by side. Reminds me a bit of the doublespeak we got from the son of a magazine company owner a while back. Lets face it this guy is being paid to add confusion and stir the pot to make his company's product look better. They can't sell their product on it's merits. The 300 BLK is a great product if you want to shoot subsonics thru a can. fine. The 6.8 is better for hunting, target shooting and HD.

AAC/rsilvers is working very hard to confuse and discredit the 6.8 because it has the biggest market share next to the 5.56mm. He's trying to make potential buyers think twice about the 6.8mm by confusing them. He's doing it everywhere. It would not surprise me if there are multiple accounts being used in forums all over the place to meet this goal.
I respectfully request this thread be closed and if rsilvers ever tries this again that he be banned.

sfsmedic
08-08-2011, 01:18 PM
LMAO and I was trying to keep it nice so I didnt get the inevitable IM from you guys. However you hit the nail on the head right there! Its a proven behavior by this individual to attack what appears to be the biggest competition of his product that he designed (stole), the black (whisper). This behavior displays the inability to create his own chamber from scratch, leading me (and I am sure others) to believe that the next step to promote or improve his design (not really his but for arguement purposes) is to attack other well proven designs with utter rubish. The second portion is to try to make that rubish sound better than it is by trying to sound like its been backed scientifically yet no scientific research is valid without data, backing it or that data is always either someone elses and old and subsequently disproven by the new data (posted here) or said to be unable to be produced which further makes it not valid.

As much as Id love to see Slivers banned I think it would hurt us more Tack. If hes banned he cant come on here trying to defend himself while we constantly and consistently squash him as a community. That squashing helps us more than him. Anyone that googles the arguement being made on other forums wont find the defunct arguement here because it would not have happened because he was banned. Also he drives my post numbers up by poking holes in his lack of scientific data that he claims is backed scientifically.

SpeakEz
08-08-2011, 01:26 PM
After reading this whole thread, the only thing I took away from it was Silvers bashing H's work. Just page after page of him saying that H needs to change his design.

Now I have only been here for a short while, but even I would know that this is not the place for that. Try somewhere else (and I guess he has) that hasn't had the majority of its members 100% satisfied with what H offers. I know where I will be going when it comes time to buy a barrel.

My only question is: How could any company stay in business if it wasn't producing a product that worked? And from what I hear, not only does it work, but is considered one of the best. All sounds pretty silly from my POV. If it ain't broke don't fix it!!

sfsmedic
08-08-2011, 01:32 PM
SpeakEz you will see this on a cycle. He does it about every 3 weeks. Same song and dance. You are right in every aspect of your post btw.

TackDriver68
08-08-2011, 01:36 PM
I'm glad I'm not the only one who sees the rubs here. They are going after the biggest competition; the 6.8. And even though I don't have one, I do think H has the best barrels for the 6.8; mainly because H has devoted so much of his life to building and improving rather than undermining and destroying like someone else I can think of.Numbers can be manipulated to show any catastrophic worst case you desire. The excellent real world advancements in accuracy and performance thanks to H, Art at SSA, Paulo Santos and Tim from Cardinal/Kotonics (and many others over the past years) can't be faked. It also will not be destroyed by clever and/or delusional marketing schemes, no matter how many charts they put forth.
If we all work together, we can show these clowns for what they are. May I suggest everyone put links tho this thread on other forums so they understand the context and bias in rsilvers' posts and can know their real worth(or lack there of)

rsilvers
08-08-2011, 03:19 PM
I don't believe any chamber has a 0.2770 throat so excluding that, you are basically saying you'd take a SAAMI chamber over a 6.8x43 since it HAS a 0.2775 throat..

The SAAMI chamber has the desirable (for pressure) 0.278 min throat, but also has a short leade, which increases pressures about 1500 psi. I would not place that above the 6.8x43 chamber, which has a longer leade, but a tighter throat diameter, which also raises pressure. So it is a wash. The 6.8 SPC-II has the best of both worlds in terms of not raising pressure.

rsilvers
08-08-2011, 03:22 PM
-If you are asking if a bullet has ever been stuck in a 6.8 chamber that had a 0.2770 or 0.2775 diameter throat - I have no evidence of that -

So what you're saying is this is another educated(as in 'I was paid to make this up') delusion of 'maybe in the worst case this might happen' . Thanks for the clarification.

I am saying you should not purposely make a female part smaller than the max size of a male part unless you are going for an interference fit. Palma shooters do it though, as they are ok with the risk during competition given that it may help accuracy.

rsilvers
08-08-2011, 03:34 PM
I really did not think this was too hard to follow - even with that chart I posted which is I think easy enough to read.

constructor
08-08-2011, 03:48 PM
The thing is none of the bullets on the market are .278 so it doesn't matter.
The mil isn't using our 6.8x43 chamber so it doesn't matter.
600lb fat chicks don't buy Mazda Miata's so it doesn't matter.
4 pages about something that might happen if something did exist???

angsniper
08-08-2011, 03:50 PM
Okay. I have to argue with the 600lb fat chick statement. I've seen it. It happens.... and they are usually wearing a tube top and a mini skirt.

tedhunter
08-08-2011, 03:54 PM
I made it through 11 pages and Ang's comment is the mental image that can't be unseen and will stick with me above all else ......................

rsilvers
08-08-2011, 03:55 PM
The thing is none of the bullets on the market are .278 so it doesn't matter.

It does matter for two reasons:

1. As you can see from the chart, 308 pressures went up 2900 psi even with a 0.3085 throat, which is larger than the typical 308 bullet.
2. There is runout - bullets are not in straight, so they rub on the side of the throat.

http://img708.imageshack.us/img708/8202/pressure.png

68WJ
08-08-2011, 03:55 PM
Okay. I have to argue with the 600lb fat chick statement. I've seen it. It happens.... and they are usually wearing a tube top and a mini skirt.
Spandex is a privilege, not a right, though sometimes confused as such (with disastrous consequences).

angsniper
08-08-2011, 04:04 PM
Something like this....

4218

JerBear
08-08-2011, 04:15 PM
Something like this....

4218

OK, now you've done it. Unlike the premise of this entire thread...that there is dangerous!

constructor
08-08-2011, 04:25 PM
next gen personal air bagz eww... fat bagz

constructor
08-08-2011, 04:26 PM
It does matter for two reasons:

1. As you can see from the chart, 308 pressures went up 2900 psi even with a 0.3085 throat, which is larger than the typical 308 bullet.
2. There is runout - bullets are not in straight, so they rub on the side of the throat.

http://img708.imageshack.us/img708/8202/pressure.png
Doesn't seem to be a problem in our barrels, it doesn't matter.

TackDriver68
08-08-2011, 05:12 PM
There you go again...using data from a different caliber to justify your delusions. You just don't seem to want to wrap your highly technical mind around the possibility that your numbers really don't matter to most people. You of all people should realize how how dynamic the changes in pressure between one case design to another....stop the sour grape comparisons between your apples, their oranges and our cantaloupes ....sorry for the bad joke......

Again, have you ever seen this happen in a 6.8 rifle? Have you ever seen a .277 bullet that measured .278? If so, it was not a .277 bullet and if it was labeled so that is a manufacturing error.

I am not the most eloquent in my responses, Nor am I an expert in all the calibers of the world; But one thing is clear, Your argument is relatively meaningless because you are choosing to ignore factors that do not support your statements

If you use enough pressure you could force any bullet into a smaller chamber, just like with enough effort a 600lb woman could get into a Miata. Just as people in steel competitions use .356(for 38 Special//357 magnum) cast lead bullets in .355 38 super barrels with tight match chambers and have excellent results. And as you yourself have pointed out, pressure depends on alot of factors, and you are ignoring most of them because it's inconvenient to your marketing goals. There are powders that are more temperature sensitive than the 2900 psi your chart quotes.

Here's an example where temperature and pressure are compared;

http://www.shootingsoftware.com/ftp/Pressure%20Factors.pdf

While their methodology may not be up to your standard of scientific testing. Look at the last graphic and the # 4 in the conclusion. You seem to want SAAMI to be god when it comes to numbers, and yet this test reveals that they virtually ignore the variables of powder temperature and barrel temperature in their testing. The test author could not find a direct requirement for temperature in the published testing standard. The results show a 7000 psi change based just on temperature change. That equates to about 200psi per degree. That means me going from 75 inside my house to the 95+ degree range is potentially 2-3 times bigger change in pressure than your fantasy phantom chamber bullet diameter 'problem' would cause. You may very well control the temperature variable in your pressure testing, but even if you do I'm fairly certain most do not.

There is also the matter of temperature of the chamber and barrel. All metals expand and contract at different rates, but it is entirely possible that a a chamber that measures too tight inside a lab at 68 degrees will be just fine outside in the summer heat. Conversely a barrel that seems fine on a bench in July could be a dangerous problem in December.Luckily, as temperatures make chambers tighter, most powders burn slower and with slightly less pressure.

Throw on top of that pressure changes caused by primers, bore diameter, case thickness or altitude and humidity. Not to mention manufacturing deviations between lots of a given powder.

RSilvers; There are many variables that affect pressure, some greater than others. For you to have the audacity to pick and choose the ones that benefit your marketing case while at the same time ignoring the ones that don't is rather petty and low class IMHO.

Munkie667
08-08-2011, 05:38 PM
In my years as a US Navy Eletro/Mech/Radar Tech (Fire Controlman). We would get the engineers That never leave the white rooms and get some brilliant ideas... That works wonders on paper and Computer simulation. We called them 200 pound heads. Some of them were great at real world application of their ideas. Others, well they never took the red pill to leave the white room, and they still live in a perfect world where things like rough seas or high winds never happen. I am not saying that is "you". What I am saying is that you are only taking data that you can make pretty in a white room that fits your ideals. Take H up on his offer. Prove to us all that you are right. Not in the white room but on the range. I am tired of seeing the same .308 pressure chart. It proves nothing for the 6.8x43.

V/R

FC1

TackDriver68
08-08-2011, 05:45 PM
On a side note, Can those with chronographs please get data on their 2-3 favorite loads for summer and then we can compare this to winter to see how temperature affects the 6.8.
I think 10 rounds of each load to establish an average would be sufficient, don't forget to save 10 rounds from the same batch to test in January. Just document everything you can and I'll start a thread in a day or 2.

wolf68
08-08-2011, 05:51 PM
Here's something for you. None of us that have H's barrels or uppers, have ever had any issues whatsoever. Most of H's customers chose him because we are the one's who like to push the limits of this cartridge. We know that they have been pushed as high or higher than any other maker out there. I know for a fact that mine has been shot with some of H's hottest handloads. I've loaded a few hot one's myself. H's barrels continue to be able to generate as much or more velocity than any other make while maintaing more than safe pressures. His 16's can attain velocities equivalent to some 18's. That is real world testing. Not some theoretical classroom drama based on data generated by a computer.
I don't know about the rest of you, but every time I see Mr. Silvers name on a post here, I get the same reaction as I do when I see Obama having a press conference. He is a Remington shill and nothing more.

sfsmedic
08-08-2011, 05:55 PM
Here's something for you. None of us that have H's barrels or uppers, have ever had any issues whatsoever. Most of H's customers chose him because we are the one's who like to push the limits of this cartridge. We know that they have been pushed as high or higher than any other maker out there. I know for a fact that mine has been shot with some of H's hottest handloads. I've loaded a few hot one's myself. H's barrels continue to be able to generate as much or more velocity than any other make while maintaing more than safe pressures. His 16's can attain velocities equivalent to some 18's. That is real world testing. Not some theoretical classroom drama based on data generated by a computer.
I don't know about the rest of you, but every time I see Mr. Silvers name on a post here, I get the same reaction as I do when I see Obama having a press conference. He is a Remington shill and nothing more.

Wolf I cant help but poke fun that your sporting a pic of the blk may cause envy pic as you discuss H's strong points on his barrel and how happy his customer base is. Just to funny.

wolf68
08-08-2011, 06:06 PM
Well, it's just another fact based observation. If it wasn't those folds involved wouldn't feel the need to bash the 6.8 and would just get on at trying to sell the .300 on it's own merits. The fact that it's proponents need to do so is proof of it's shortcomings. The same can be said of Remington's handling of the 6.8 at it's inception, and it's continuing ignorance of the facts as they exist concerning this round.

DDriller
08-08-2011, 06:29 PM
Okay. I have to argue with the 600lb fat chick statement. I've seen it. It happens.... and they are usually wearing a tube top and a mini skirt.

Had to be out of state. LMAO

RugerIte
08-08-2011, 06:42 PM
I need a clarification please. To be an expert do you have to be out standing in your own field or will any field do? I got access to an old hay field it that helps me be an expert!

Really if SOME ONE would just SAMMI a decent Spec II configuration they would see a big jump in sales. I think there might be a Ruger/Hornady collaboration maybe. OR just Hornady, a 6.8X43 "Your Name Here!" SPC would get who ever ponied up and SAMMIed it a lot of free advertising.

One way to explain it to some one is as a +P to a laymen who might think the cartridge changed and not the chamber. Explaining the chamber can handle the a +P version of the same sized cartridge would easily clear things up why the newer chamber is better as it could shoot BOTH cartridge loadings.

Really with all those DOA cartridges that get SAMMIed, why do they drag their feet on a proven performer?

From what was done in the only "Public" showing of pressure tests from the 2008 report, and experience from hand and hot loaders and in between, I don't think their is a problem. I got a 6.8X43 and may shoot just factories, but with now Spec II ammo ONLY coming out I see it was a wise investment.

Silvers is the new Remington 6.8 SPC ammo going to have bigger bullets than normal, by the sound of your concerns I hope that ain't true.

Really a proper SAMMI speced SPEC II by even Remington would be appreciated. Most people stopped blaming Remington for the SAMMI gaff as they used the specs submitted to them. It would sure be nice if they helped get a true properly Speced SPEC II chamber SAMMIed.

Constructor...those BARRELS were shooting OK when I was in line for one? :a39: OH well I didn't own a any sort of field like a corn or old hay field to be an expert on if they were safe or not. So I still trust yer judgement it still was a right decision. Besides my ER SHAW still places shots great. :a04:

Hmmm wonder if this will be on same page I stopped reading it as...

NOTE: At the moment I'm not out standing in any sort of field so cannot be considered an expert!

Nope on a new page....

OK...now some one I consider an expert down below this post. Seems to make sense.

-k-
08-08-2011, 06:43 PM
Have you ever seen a .277 bullet that measured .278? If so, it was not a .277 bullet and if it was labeled so that is a manufacturing error.

Did you read the SAAMI spec?
http://www.saami.org/PubResources/CC_Drawings/Rifle/6_8mm%20Remington%20SPC.pdf
The SAAMI spec for the bullet diameter is .2780" -.003", so .2780" would be in spec. There is not a more accepted "standard" in the US than SAAMI that I know of.

And before anyone claims Remington must have messed up the bullet diameter here is the spec for the 270 Winchester.
http://www.saami.org/PubResources/CC_Drawings/Rifle/270%20Winchester.pdf


Look, I've read that study on neck diameters and pressure before. The testing showed a direct pressure to throat diameter difference in each of five different test barrels. The testing method and data looks to be correct. So I have to ask why anyone would expect the results to be different with the 6.8?

Is seems that some would rather have a bit of accuracy potential and some would rather have a safety margin for bullets on the high end of the spec. Both are fine in their own way and I see no need for the emotional responses. I agree with the original quote, for a military type weapon reliability should be first. For hunters and handloaders the tight throat is fine, as long as they realize that there "could" be an issue with bullets made to the max spec.

constructor
08-08-2011, 06:57 PM
I know guys that shoot .311 bullets in a .308 bore, hasn't killed them yet.
A barrel is .277 dia in the groove for 14" the throat is .095" long and .2775" diameter so which is going to create more pressure if the bullet is larger than the nominal bore diameter?
Hey Slivers maybe we should make the bore bigger to keep the pressure down, just let them bullets rattle their way out of the barrel.

kalwasart [Member]
7/5/2006 12:40:10 PM MDT

Randall, check your 6.8 reamer drawing, at the 45 degree angle at the .2781 lead, is it 1.70185? I have received several drawings from different gun manufactures that have that same dimension. But from another gun manufacture I have 1.7109 which I believe is the correct dimension.

If the 1.70185 is being used that means the 45 degree angle can not exist and you will end up with a sharp corner at the lead into the chamber. The X-Treme combat loads needs this angle otherwise pressure will peak.

I have a 5 inch thick file on testing on the 6.8 and have to come to the following:

1. Neck size does not have anything to do with increasing pressure and I have the computerize test result to prove it.
2. Cartridges has to be made to the low end of the spec with regards to dimensions.
3. Recently found errors in chamber reamer drawings developed a sharp corner leading into the chamber, which is effecting the X-Treme combat loads. In the June issue of SWAT the Combat X-Treme had excellent results out prefoming all others rounds. You can blame the X-treme all you want but it works in some guns and not in others, so you decide, is it the ammo or the weapon? We however made adjustments to the X-treme to work in weapons with chamber issues.
3,. If your weapon can not shoot projectiles at 2,650 FPS than you have a weapons problem.
4. Some guns have very bad timing problems, where the bolt is trying to open while still under high pressure. Cases ejecting from the 1 to 3 o'clock position. The hotter the load the bigger the problem becomes.
5. If the case are blowing primers and expanding above .424 (being max chamber SAAMI) this is direct result of the bolt opening early.

Our triple Shock thru a Barrett and CMMG is getting 2,715 FPS, can your gun handle it?

The Military has tested the X-Treme at velocities of 2,625 FPS and had no problems. But again who's weapon did they test it in.

We have made changes to the X-Treme so it will work with all weapons, mainly down loading it. We are try to offer a good round at a reasonable price unless everyone wants to shoot just the expensive stuff.

If I was a gun manufacture I would be asking myself if a round is working in someone else gun why is it not working in mine? Or the quick answer is Blame the AMMO.



Art - SSA

-k-
08-08-2011, 07:03 PM
H's barrels continue to be able to generate as much or more velocity than any other make while maintaing more than safe pressures.
I don't think you can say that without knowing the actual pressure. Pressure signs are not a reliable as most handloaders make it out to be, or we would see pressure signs in factory WSM ammo.
I would also expect it's the bore ratio, not the tight throat that allows higher velocity.


His 16's can attain velocities equivalent to some 18's. That is real world testing. Not some theoretical classroom drama based on data generated by a computer.
Test pressure barrel testing is not generated by a computer or theory. It involves firing a cartridge with a pressure sensor touching the cartridge case to measure pressure.
http://archives.sensorsmag.com/articles/0599/0599_p93/index.htm

constructor
08-08-2011, 07:12 PM
What would create more pressure a .2775 throat .095 long in a barrel with a 70:30 groove to land ratio
or a .278 throat with a 50:50 groove to land ratio barrel? Many 6 groove barrels on the market approach 50:50 but you think they are ok as long as they have a .278 throat?
I can tell you without a doubt they blow primers long before the 70:30 ratio barrel does. 2 different high end stainless match grade barrels from different 6.8 producers.

ArtFWTx
08-08-2011, 07:38 PM
What would create more pressure a .2775 throat .095 long in a barrel with a 70:30 groove to land ratio
or a .278 throat with a 50:50 groove to land ratio barrel? Many 6 groove barrels on the market approach 50:50 but you think they are ok as long as they have a .278 throat?
I can tell you without a doubt they blow primers long before the 70:30 ratio barrel does. 2 different high end stainless match grade barrels from different 6.8 producers.

Facts don't work with the high counsel of BO. It's more of the same. He has a one way thought process... out. No inbound messages accepted.

TackDriver68
08-08-2011, 07:42 PM
It's all marketing....when you cant sell a product on its merits alone you soil the competition. nothing more.


Guess I'm going with Surefire when I decide to get that can. Thanks for helping with the decision.

sfsmedic
08-08-2011, 08:06 PM
I've literally sworn off all AAC and affiliates because of this guy. Savage got my business on the bolt gun seriously because of Slivers. Hope you're reading this Remington.


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Munkie667
08-08-2011, 08:10 PM
As much entertainment as I got from this thread over the last two days I think this is done.

R.S. I just want to thank you for so much fun.

0311
08-08-2011, 08:17 PM
I've literally sworn off all AAC and affiliates because of this guy. ....

I agree completely. I may be a bit biased as I am a very satisfied owner of one of H's piece of art barrels. I had not discredited AAC, and in fact didn't know anything about them until reading this thread (yes, I'm new to these forums), but with business practices I've seen in this thread, they will never be an option in my book.

346CI
08-08-2011, 08:21 PM
It's all marketing....when you cant sell a product on its merits alone you soil the competition. nothing more.


Guess I'm going with Surefire when I decide to get that can. Thanks for helping with the decision.

I bought a Element when they first hit the scene, nice can but damn expensive for what it is. If I had to do it all over again after reading this 'tards comments, I would have went with a Sparrow. No more AAC stuff for me......

SixEight
08-08-2011, 08:31 PM
The emotional response has not come from Silvers' opinions and advice if misguided. They've come from the fact that he insists upon going to every forum on the web and injecting himself into every single 6.8 discussion. Not only that, he won't make his opinion known and shut his pie hole but he continues to argue time after time after time. We were in a discussion about why 6.8 hadn't "taken off" as somebody put it and he continues to argue that it should have been named .270 (something or other.) Something ridiculous as that and he tries to make it into a fact based argument over something so opinionated.

The time and effort he has spent on 6.8 seems disingenuous and greed motivated which no one takes kindly to.

I was sold on the 6.8 long before I came across his negativity and even if I would have been interested in his cartridge, I am soured to it now. That is all.

[edit]
Oh and I almost forgot. Thank you Silvers for making me dive deeper into the spec. You've made me even happier about my decision that the 6.8 is the superior cartridge FOR ME. Even though I'm not a hunter I don't think people should think of it as purely a hunting round.

Overton-AR
08-08-2011, 08:33 PM
Threads like this one are the reasons that I buy my suppressors from GEMTECH and SILENCERCO.

6.8henry
08-08-2011, 08:41 PM
H
you made me the most accurate AR I have ever owned. I will soon be ordering another for my oldest son, and possibly more if my other boys show interest in having their own as well. My ARP upper has outperformed two others 6.8 spc I uppers by far. We all have cooked up our own handloads and min upper is the only one that handles all of them with no pressure signs, swipes, primer issues or stuck cases. My ARP upper is also the only one that all of us can consistently shoot under 1MOA.

TackDriver68
08-08-2011, 08:41 PM
I say he should be required to notify us 45 minutes before his next post so we can clear our schedules and make popcorn & nachos.

http://1389blog.com/pix/alarmed-popcorn-smiley.png

sfsmedic
08-08-2011, 08:48 PM
I have to admit I decided to google this guy and I'm laughing at one of the very first posts I read. It starts like this.

"Is it just me or does it appear that Mr. Silvers has momentarily stopped coming around to spread the ludicrous claims surrounding the BRAND NEW AAC 300 BLACKOUT?

I mean I miss reading about rocket science, voodoo, and skilled machinists who are the only ones who know how to read and follow a blueprint.

Wonder what the next load of bullsh*t AAC/Silvers is going to try to feed us next?



Anyways .. back to your regularly scheduled program!"
DS762 www.quarterbore.com.

Nice to see he rubs everyone the same consistently across the web.





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angsniper
08-08-2011, 08:49 PM
... and you thought I was kidding...
4225

TackDriver68
08-08-2011, 08:49 PM
Can't see it

TackDriver68
08-08-2011, 08:50 PM
fixed...tag for epicness

sfsmedic
08-08-2011, 08:51 PM
Yeah I cant see anything Ang posts, odd!?!?? Nm just opened it in its own tab.

ppapago
08-08-2011, 08:59 PM
Never in my life have I experienced such a display of trolling. This past couple of days has been a real treat. My money will never go AAC's way. That display was so tragic it was comical.

68WJ
08-08-2011, 09:02 PM
I think all that can be said has been. We looked at some SAAMI info, some charts, heard from users and engineers, and momentarily discussed fat women in Miatas. There should be enough here for anyone to draw their own conclusions one way or another.

Jamesb74
08-08-2011, 09:09 PM
Here is my two cents and probably no one will like it.

1. RSilvers data and argument is extremely one sided. The data and reports and graphs are taken from one point of view with one result. It is all based off of the testing of what it will take to get something approved by the .mil or LEO agencies with no regard and complete disdain for anything else or any other data. Yes it is very one sided and very much only geared towards one final goal. And the lack of even trying to accept other data or viewpoints is extremely disappointing. How a lab coat cannot understand that there is more then one way to skin a cat and more then one way to get things done is beyond me.

2. The rest of you are absolutely ridiculous. Constructor, -k-, the OP, and a couple others are the only one's that debated with facts and or asked questions that were relevant to the discussion. everyone else just jumped in with bull**** comments intended to disrupt the conversation and try and get a rise out of the OP and show how big your cock is. That is complete and utter bull****. People here ( some of the ones that caused all the bull****) complain that this place is becoming more and more like ARFcom and yet they are the ones contributing to it. How about this for an original idea. If you dont have a ****ing clue or fact or relevant question to add to the conversation that is not inflammatory how about you STFU!!!!!

See I told all of you that you wouldn't like my opinion. It is up to you to understand.

Jamesb74
08-08-2011, 09:11 PM
I think all that can be said has been. We looked at some SAAMI info, some charts, heard from users and engineers, and momentarily discussed fat women in Miatas. There should be enough here for anyone to draw their own conclusions one way or another.

Your right this thread is done