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AKsarben
03-13-2010, 10:21 PM
I got some IMR 8208 XBR powder yesterday, and have loaded up some test loads for accuracy. While I was loading up a series of bullets I tried 2 different grain weights and one different case mfg for testing of initial pressure.

EQUIPMENT: Rock River Arms 6.8 SPC II upper 16" barrel with 1:10 twist, mid length gas system.
Adams ARms Piston system for mid length system.
Silver State Arms and Hornady brass
CCI 450 Small Rifle Magnum primers
Hornady 100 gr SP bullet (flat bottom)
LEE sizer die and LEE Factory Crimp die Fired once brass except for the Hornady (2) and full resized.

Powder : IMR 8208 XBR, the new stuff out.

First a little clue on load data from Hodgdon site:
<TABLE border=1 cellSpacing=0 cellPadding=2 width="100%" align=center><TBODY><TR><TD class=h4 colSpan=4>6.8 mm Remington SPC
Cartridge Load Data</TD><TD class=mini vAlign=bottom colSpan=3 align=middle>Starting Loads
<HR width="100%"></TD><TD class=mini vAlign=bottom colSpan=3 align=middle>Maximum Loads
<HR width="100%"></TD></TR><TR class=toprow><TD class=mini align=middle>Bullet Weight (Gr.)</TD><TD class=mini align=middle>Powder</TD><TD class=mini align=middle>Bullet Diam.</TD><TD class=mini align=middle>C.O.L.</TD><TD class=mini align=middle>Grs.</TD><TD class=mini align=middle>Vel. (ft/s)</TD><TD class=mini align=middle>Pressure</TD><TD class=mini align=middle>Grs.</TD><TD class=mini align=middle>Vel. (ft/s)</TD><TD class=mini align=middle>Pressure</TD></TR><TR><TD class=mini align=left>110 GR. HDY V-MAX </TD><TD class=mini align=left>IMR 8208 XBR </TD><TD class=mini align=middle>.277" </TD><TD class=mini align=middle>2.260" </TD><TD class=mini align=middle>28.0 </TD><TD class=mini align=middle>2496 </TD><TD class=mini align=middle>38,500 PSI </TD><TD class=mini align=middle>30.0C </TD><TD class=mini align=middle>2690 </TD><TD class=mini align=middle>48,600 PSI </TD></TR><TR class=altrow><TD class=mini align=left>115 GR. SIE HPBT </TD><TD class=mini align=left>IMR 8208 XBR </TD><TD class=mini align=middle>.277" </TD><TD class=mini align=middle>2.260" </TD><TD class=mini align=middle>28.0 </TD><TD class=mini align=middle>2483 </TD><TD class=mini align=middle>41,800 PSI </TD><TD class=mini align=middle>30.0C </TD><TD class=mini align=middle>2647 </TD><TD class=mini align=middle>51,400 PSI </TD></TR></TBODY></TABLE>

And the relative burn rate of IMR 8208 XBR powder so you have a basis to consider withing a close margin to this powder, courtesy of Hodgdon.com web site "Powder Burn Rates" chart:

61 Hodgdon H322
62 Accurate Arms 2015BR
63 Vihtavouri N130
64 IMR, Co IMR3031
65 Vihtavouri N133
66 Hodgdon BENCHMARK
67 Hodgdon H335
68 Accurate Arms 2230
69 Accurate Arms 2460s
70 IMR, Co IMR 8208 XBR
71 Hodgdon H4895
72 Vihtavouri N530

First 2 rounds in the picture are SSA brass loaded on the left with 30.0 gr of IMR 8208 and one on the right with 30.5 grains of same powder. Bullet below the 30.0 was recovered after going through a water jug and into soft muddy soil. Both cases appear to have no excessive pressure signs. I don't have a chronograph, but judging by the recoil and the recovered 100 grain bullet, I would say it was no slouch for fps. Will have to get one or borrow one someday soon and check this.

http://vernsdidj.com/pictures/guns/AR/6.8spc/brass/8208_XBR.jpg

Next picture is of 2 SSA pieces of brass on the left and a Hornady brass on the right. All 3 have the same amount of powder, 30.5 grains 8208 XBR powder. Notice the powder levels. The case on the left is just filled with powder, the 2nd from left is slightly vibrated with finger tapping while holding a finger over the case mouth to prevent loosing powder, IE slight vibration to settle the powder. The Hornady case to the far right is the same as the case to the far left, filled with 30.5 gr 8208 XBR and unsettled. Only the 2nd to the left case shows it "looks" like it has less powder, but in actuality, it is all the same, just jiggled a bit to settle before seating a bullet on top.

http://vernsdidj.com/pictures/guns/AR/6.8spc/brass/8208_xbr_unsettled.jpg

This picture is of all 3 pieces of brass, with 30.5 gr of 8208 powder, after being "tapped" and settled. Notice that even the Hornady case on the far right benefited by this vibration to settle the powder in.

http://vernsdidj.com/pictures/guns/AR/6.8spc/brass/8208_xbr_settled.jpg

This evening, I took the Hornady cased bullet with the 30.5 gr IMR 8208 XBR powder, 100 gr Hornady bullet with an OAL of 2.278" out and shot 2 milk jugs (in-line). Both jugs completely obliterated. Bullet yet to be recovered. Case looks VERY good for pressure signs:

http://vernsdidj.com/pictures/guns/AR/6.8spc/brass/8208_xbr_30.5_hornadybrass.jpg

I included this in there as I have both Hornady and SSA brass and there may be those looking at this thread that also have Hornady and wonder about it's use with this powder. I really need to chronograph this sometime.

I imagine that with a 1:11 or 1:12 twist barrel with a SPC II or DMR-C chamber that things might even be more favorable.

This is one of the new powders developed for bench rest shooters. It was kind of an accident, in a way. They were trying to "clone" or duplicate an earlier developed powder, a T powder from the 1960s and came up with this one that actually outperformed what they were looking for in the first place. I has great temp range, from very cold -40 F to very hot conditions +165 F and still maintains consistent pressures. It is also found to be very forgiving in accuracy when the load varied a few tenths off. This was pretty important in developing loads of good accuracy.

This powder has already proven itself and won matches. To read more about this powder, and learn a bit more if you are interested I have included this link:
http://accurateshooter.wordpress.com/2009/10/03/hodgdon-releases-impressive-new-imr-8208-xbr-powder/

It is a bit on the slower side, but oftentimes, powders and burn rates can change if they are compressed and burn rates can vary from cartridge to cartridge due to the size and actual available volume inside the case. It may work out well for 6.8 SPC. If you look at Hodgdon data, it has a good velocity to PSI of the charge, at least in the 6.8 SPC. Some others are not quite as good, but then we have a very unique case design here from the onset.

Hope that you enjoy the link and what brief amount of info I have to share at this time.

Bushdog45
03-13-2010, 11:29 PM
AK, thanks for the report on the new powder. I assume the data was from a 24" test bbl.? Be interesting to see what vel. the 16" loads bring. How was the accuracy?

AKsarben
03-14-2010, 01:40 AM
Waiting to test out the accuracy at the range. Maybe tomorrow. Hodgdon data said it was a 24" barrel wiht a 1:10 twist barrel, using Remington 9 1/2 Large Rifle primers and Remington cases. Likely was a SAAMI non-modified SPC II chamber.

AKsarben
03-14-2010, 09:02 PM
No range time today (cold, windy) but did do some more pressure testing. Went from 30.5 to 32.0 by 0.3 grain increments. No flattened primers nor ejector swipes. Case web showed some expansion, but it was at 0.421" with the 32.0 grains, same as it was on the earlier load.

Powder fills up about half way up the neck, even when jiggled down a bit at 32.0 gr. 100 gr Hornady bullet with OAL of 2.280" and a light LEE factory crimp. SSA brass.

One thing I have noticed and even my wife commented on it, was that it really has a loud report. She likens it to a cannon going off. LOL I've watched, and my daughter watched the end of the barrel looking for a powder flash indicating unburned powder outside the end of the muzzle. No flash. Found the remains of the bullet shot the other night from the Hornady case. Jacket all peeled away and lead separated from the jacket.

Would be nice to have some sort of pressure equipment to see where I am at. I don't have data for the 100 grain Hornady listed from Hodgdon for reloading, only the 110 gr. So it may take a bit more than 32.0 grains to get up to absolute top pressure. There's a bit of room left in the case, but I really think it's a matter of heavier compression to get any more in there past 32.4 grains.

EWP
03-15-2010, 03:03 AM
Hodgdon doesn't start listing 8208 XBR until 110 gr bullets since it's so slow and max is 30 gr's at 2690 FPS, 48,600 PSI but this is at 2.260" COL.

AKsarben
03-15-2010, 07:52 AM
Hodgdon doesn't start listing 8208 XBR until 110 gr bullets since it's so slow and max is 30 gr's at 2690 FPS, 48,600 PSI but this is at 2.260" COL.

....and it's for a Remington case that may have less capacity than that of the SSA case. Along those lines, they probably only had, or worked with, SAAMI original chamber dimensions, and the 1:10 twist barrel.

110 grain bullet traveling 2960 out of a SAAMI chambered firearm, doesn't seem that bad for the pressure generated. There may be powders to push the 110 gr bullet as fast or faster than 2690 fps, but do they do it at under 49,000 PSI pressure?

Drifter
03-15-2010, 10:10 AM
Good info Vern.

Now, if we could only talk you into getting a chrono...

AKsarben
03-15-2010, 10:42 AM
Good info Vern.

Now, if we could only talk you into getting a chrono...

Friend at work, Glen is going to lend me his chrronograph. He suggested I get my wife one for Mother's Day, and see if I can "borrow" it once in a while. :a15:

AKsarben
03-15-2010, 11:58 PM
Picstures of 4 loads I tried today. It was a little windy, not bad, and cool. What I found intersting is that the shots all held close groups even when I went from 29.7 gr to 30.5 gr in 0.3 grain incriments. One the one group, the last group with 30.5 gr 8208 powder, I knew at the moment I pulled the trigger it was going to be off (second shot). Really concentrated and put the 3rd shot right next to the first. ALL of the squares are 1" grid pattern if you like to figure the distance of the groups. Even with that last one messed up a bit on the second shot, it was not that bad of a group. Adams Arms Piston system as well.

29.7 gr. a 5 shot group getting the barrel "accustomed" to the carbon of the 8208 powder.

http://vernsdidj.com/pictures/guns/targets/6.8spc/29.7_8208XBR.jpg

30.0 gr

http://vernsdidj.com/pictures/guns/targets/6.8spc/30.0_8208xbr.jpg

30.3 gr

http://vernsdidj.com/pictures/guns/targets/6.8spc/30.3_8208xbr.jpg

and 30.5 grains where I pulled the second shot a bit.

http://vernsdidj.com/pictures/guns/targets/6.8spc/30.5_8208xbr.jpg

Awaiting a chronograph to see where it is shooting. One thing I really like is that I can dump powder straight from the powder charger into the case (when I get it consistents on gr weight) and not worry too much if it's off 1-2 tenth between shells.

AKsarben
03-16-2010, 09:48 PM
Shot some loads though a friend chronograph today. 100 gr Hornady SP, SSA brass, CCI 450 primer and IMR 8208 XBR powder.

31.3 2657 fps
31.3 2694 fps

31.7 2719 fps
31.7 2676 fps

32.0 2725 fps
32.0 2738 flps

32.0 grains gave me about half way up the neck in the case. With a 100 grain bullet how is this?

One other consideration is the elevation of where I live. SW Michigan, near the Lake Michigan shore with an elevation of around 650 ft above sea level. I used my friend older chronograph, red and shows "Shooting CHRONY" on the top of the folded up box. Only on switch is inside, and is powered by a 9 volt battery.

Drifter
03-16-2010, 10:13 PM
Shot some loads though a friend chronograph today. 100 gr Hornady SP, SSA brass, CCI 450 primer and IMR 8208 XBR powder.

31.3 2657 fps
31.3 2694 fps

31.7 2719 fps
31.7 2676 fps

32.0 2725 fps
32.0 2738 flps

32.0 grains gave me about half way up the neck in the case. With a 100 grain bullet how is this?

One other consideration is the elevation of where I live. SW Michigan, near the Lake Michigan shore with an elevation of around 650 ft above sea level. I used my friend older chronograph, red and shows "Shooting CHRONY" on the top of the folded up box. Only on switch is inside, and is powered by a 9 volt battery.

Not bad. Thanks for sharing chrono results.

My interest with 8208 is how well it might work with the Nosler 100gr AB and the soon-to-be-released Barnes 95gr TTSX. If velocity can be 2775 to 2825 fps, along with good accuracy using a temp-stable powder, it might be a worthy candidate.

For what it's worth, my experience indicates that Nosler 100gr AB's will be ~50 fps faster than Hornady 100gr SP's with the same load, although the Nosler might require more powder compression for the same COL.

How well does 8208 compress?


ETA- As a comparison, 30.0gr of 10X gave me approx the same velocity with Hornady 100gr SP's as you got with 32.0gr of 8208. My data is from a previous upper with an 18" barrel. Using 30.0gr of H322, velocity was ~50 fps slower. Both loads were with CCI#41 primers. ~100' above sea level. (These loads were safe in my rifle. Always start low and work up.)

EWP
03-17-2010, 06:36 AM
Powder is a little slow for the mid-lighter bullets as you can tell with the low pressure at max charge, with a 32 gr charge and 100 gr bullet you should be closer to 2900+ FPS with the right powder, now what powder that is I don't know yet but will find out, but 8208 should be great with the 110 & 115 gr bullets.

AKsarben
03-17-2010, 10:36 AM
On Glen's chronograph, he has some vineyard wire for the replacemnt wire. Others got shot. It's just the wires sticking up. I have seen chronographs on the net, and they have a diffuser on top for the light. Is this necessary?

Drifter
03-17-2010, 10:42 AM
I have seen chronographs on the net, and they have a diffuser on top for the light. Is this necessary?

I think it depends upon the lighting. If you get readings without it, no need to worry.

Dussander
03-17-2010, 12:39 PM
Chrony replacement wires and the plastic top pieces are real cheap to replace. Don't ask why I know.

AKsarben
03-17-2010, 03:23 PM
At noon shot some more. 2690, 2714, 2743 with the 100 gr Hornady and 31.0 gr of 8208 XBR

I loaded 1 Sierra bullet, a 110 gr Flat Base Spitzer bullet with 31.0 gr of powder, which is about 1 grain over the recommended by Hodgdon. Brass, and primer are ok, no signs of pressure. Bullet seated in pretty deep, just below the neck and with the powder 1/2 way up the neck it was defenitely compressed, still, no over pressure signs. 2664 fps out of 16" barrel, 1:10 twist SPC II Rock River Arms upper, Adams Arms Piston.

Question: How fast is fast enough? At these speeds, the 100 Hornady is literally coming apart. The groups are very tight which I kind of like. Would be a nice round for practice for sure. VERY accurate powder.

AKsarben
03-20-2010, 12:07 AM
Target of 31.0 gr IMR 8208 XBR with a Sierra 110 gr Spitzer bullet (flat base). I like the idea of getting away from boat tail bullets as I think they can make the bullet longer and take up valuable room in the case.

http://vernsdidj.com/pictures/guns/targets/6.8spc/31,0gr_IMR8208_XBR-110sierra.jpg


The squares are 1" square. Not too bad for a piston set up, huh?

EWP
03-20-2010, 07:39 AM
Whats a piston setup got to do with accuracy:a40:

Not bad though, you should shoot 5 shot groups since it's hard to get a real average of consistency with only 3 shoots.

Weather permitting I'm going to test some 90 gr TNT's w/c and 100 gr Accubonds through my new chronograph tomorrow and see how it works and what kind of velocity I'm getting from Benchmark up to 32 gr with the 90 & 100 gr bullet. Lyman list 2966 FPS with 31 gr's of BM so we'll see what one more gr and a better barrel will give us. I want to load some 90 gr TNT's with 29.5 RE7 before I go because this is a well known load to compare my velocity #'s to and if I have time I might load a few 100 gr bullets with 10X also, everything's last minute for me but hopefully I'll get to test something if it's not raining.

AKsarben
03-20-2010, 11:02 AM
Whats a piston setup got to do with accuracy:a40:

Not bad though, you should shoot 5 shot groups since it's hard to get a real average of consistency with only 3 shoots.


Thanks EWP! The piston comment is that there are MANY (and I stressed that word) that insist and post that a piston driven AR is less accurate than a DI gas system rifle with the same barrel, etc, with the only change being form gas DI to Piston. I believe I have even read it in some of the gun rags concerning the same thing. Adams Arms does something that is beneficial, and not sure that a lot of other piston systems do this. They eliminate the 3 gas seals on the bolt and have a heavy spring in there to keep the bolt forward. They have explained to me (John@adamsarms.net) that this keeps the bolt in battery to affect the timing to be more like the DI timing on the AR-15.

I certainly agree with you on the 5 shot groups. I even think 10 shots give a better feel for absolute spot placement for the scope and a better representation. However, I shoot a lot of 3 shot groups just to see where it is "looking". If I shoot 3 shots and they are all over and scattered around, it just saves bullets and powder (some bullets at 27 cent each) to waste on an additional 2 shots of a bad load. I have had some 3 shot groups that were not groups by any means. If 3 can't get within 2 inches of each other, then why bother shooting 5? http://68forums.com/forums/images/icons/icon10.gif

Let us all know how the 90 gr TNT turn out. I have some on order from Midway. I really think that the IMR 8208 XBR is a good powder, but may be limited to what bullets one loads from 110 on up to 130 gr. I don't have any RE7 but have some Ramshot X-Terminator. Wondering if that would be close to the same velocity/energy of the RE7?

EWP
03-20-2010, 03:50 PM
Thanks EWP! The piston comment is that there are MANY (and I stressed that word) that insist and post that a piston driven AR is less accurate than a DI gas system rifle with the same barrel, etc, with the only change being form gas DI to Piston. I believe I have even read it in some of the gun rags concerning the same thing. Adams Arms does something that is beneficial, and not sure that a lot of other piston systems do this. They eliminate the 3 gas seals on the bolt and have a heavy spring in there to keep the bolt forward. They have explained to me (John@adamsarms.net) that this keeps the bolt in battery to affect the timing to be more like the DI timing on the AR-15.

I certainly agree with you on the 5 shot groups. I even think 10 shots give a better feel for absolute spot placement for the scope and a better representation. However, I shoot a lot of 3 shot groups just to see where it is "looking". If I shoot 3 shots and they are all over and scattered around, it just saves bullets and powder (some bullets at 27 cent each) to waste on an additional 2 shots of a bad load. I have had some 3 shot groups that were not groups by any means. If 3 can't get within 2 inches of each other, then why bother shooting 5? http://68forums.com/forums/images/icons/icon10.gif

Let us all know how the 90 gr TNT turn out. I have some on order from Midway. I really think that the IMR 8208 XBR is a good powder, but may be limited to what bullets one loads from 110 on up to 130 gr. I don't have any RE7 but have some Ramshot X-Terminator. Wondering if that would be close to the same velocity/energy of the RE7?

Xterminator is closer to H335 and does OK because you can fit so much in the case but is still a little slower than optium for 85-100 gr bullets.

It's rained today and is very cloudy so I didn't bother with the chronograph but did load some extra 90 gr TNT's with 29(fowler shots and to settle powder change in barrel), 29.5, 30, & 30.5 for velocity testing along with the loads of Benchmark to see which will be most consistent at highest velocity.

Looks like I'm going to have to get the light kit for the chrono and do some velocity testing indoor since most weekends where I can shoot out to 100 yards get ruined some how every time, I just hate not getting the grouping data at distance while doing the velocity test to also keep from wasting my 100 gr Accubonds on just a speed test.

cliff444
03-20-2010, 10:19 PM
Actually, chronographs work the best on cloudy days. It's the sunny ones that screw them up. On cloudy days you do not need sky screens.

EWP
03-20-2010, 11:42 PM
Actually, chronographs work the best on cloudy days. It's the sunny ones that screw them up. On cloudy days you do not need sky screens.

Thanks for the tip, it was raining also so still a no-go(damn I wanted to go bad and it's supposed to be rain & snow slush mix tomorrow but Monday is going to be bueatiful and almost 50*, go figure:mad:).

If less light is good then why do you need lighted sky screens when shooting indoors? other than the florescent light issue, my indoor range used halogen lights I believe.

If one where to try and make his own lighted sky screen what type of lights would be best(LED?) and when do you need the light sky screen other than indoor ranges?

cliff444
03-21-2010, 01:28 PM
Actually, there is better light when cloudy because the light is diffused already. There are light kits available for most of the chronys for indoors that are not all that expensive. If you get a CED millennium, you can get infrared skyscreens and can shoot through them in total darkness if you want. I have not tried it yet, but one fellow i talked to took a sheet of cardboard that was white on the side and wrapped it to form a tube. He placed his chrono in it and put a 90 degree flashlight in it facing up. Said it worked just fine. If you have any kind of fluorescent lights, you need to turn them off. They would screw up even my Oehler when I had it. I now have a Prochrono pal, and it works just fine, and was cheap. Couldn't justify the Oehler when they were bringing $600 on EBAY a couple years ago after they were discontinued.:a01:

Curly
03-21-2010, 06:56 PM
I'm currently shooting a Stag 6.8 SPC 1:10
Would you recommend IMR 8208 XBR for a non-SPC II chamber?
I assume I'd have to reduce the charge somewhat, to achieve the 2550 fps range.

cliff444
03-21-2010, 07:58 PM
Didn't know Stag produced a barrel that was not spcII and 1:11. Better call customer service.

AKsarben
03-22-2010, 12:07 AM
When you compare the velocity of IMR 8208 XBR of 2624, 2657, 2635 with the 110gr Sierra Spitzer and the reloading data complied by Tim in an Excel file here: http://68forums.com/forums/showthread.php?t=476 it seems to hold it's own very well against some of the other contenders, even though it's a bit slow.

EWP
03-22-2010, 04:42 AM
I would just stick with h322 & 10X for the 110+ gr bullets but X-Terminator and H335 do well also.

AKsarben
03-22-2010, 12:33 PM
Yes, but those powders are a lot more grain sensitive for accuracy rounds. This one, the IMR 8208 XBR is giving me very good groups whether I weigh each powder charge ot simply "throw" it from the powder charger. It is nice to not have to worry about small differences in grain weights to throw off the accuracy.

dntfxr
03-22-2010, 02:08 PM
That's good shooting, even if it's not screaming velocity. It definitely seems to like that powder with a variety of charges.

AKsarben
03-23-2010, 09:50 PM
Thanks!!

Here are some fps figures of today. SSA brass, 31.0 gr of IMR 8208 XBR, CCI 450, 110 gr Sierra Spitzer flat base.

2560
2578
2579
2534
2563

Can someone that has the info tell me what the S.D. of this series of 5 shots would be?

I also shot a 90 gr Speer TNT with 31.0 gr of Reloader 10X, Hornady brass (no SSA resized). Velocity was 2998 fps.

JerBear
03-23-2010, 10:05 PM
Thanks!!

Here are some fps figures of today. SSA brass, 31.0 gr of IMR 8208 XBR, CCI 450, 110 gr Sierra Spitzer flat base.

2560
2578
2579
2534
2563

Can someone that has the info tell me what the S.D. of this series of 5 shots would be?
.

Standard Deviation=18.24

EWP
08-12-2010, 08:17 AM
I picked up 2lbs of the IMR-8208 XBR to test with the 110gr Hornadys and Accubonds to see if I can up the velocity a little since the pressure with this powder is so low and also keep the accuracy for my hunting loads. I can get screaming velocity and good accuracy from 10X but the pressure is on the very high side so I figured I would give this powder a shot and see how it does(I good about getting more powder in the case than most:a26:)

Post Toastie
10-15-2013, 11:29 PM
Any updates or new loads for this powder?

luvmymini14
10-16-2013, 12:59 AM
Consensus seems to be that it is too slow for 6.8. Better speed and good accuracy from 10x and aa2200 as well as H322. Look at JWTharpe's results with LT-32 as well.

chasw
10-16-2013, 08:46 AM
Shot some loads though a friend chronograph today. 100 gr Hornady SP, SSA brass, CCI 450 primer and IMR 8208 XBR powder.

31.3 2657 fps
31.3 2694 fps

31.7 2719 fps
31.7 2676 fps

32.0 2725 fps
32.0 2738 flps

32.0 grains gave me about half way up the neck in the case. With a 100 grain bullet how is this?

One other consideration is the elevation of where I live. SW Michigan, near the Lake Michigan shore with an elevation of around 650 ft above sea level. I used my friend older chronograph, red and shows "Shooting CHRONY" on the top of the folded up box. Only on switch is inside, and is powered by a 9 volt battery. AK: It appears you have a very accurate rifle and the shooting skills to take advantage of it, congrats. However, the velocities you are getting from a 16" barrel demonstrate that 8208XBR is way too slow for optimum performance in the 6.8 with 100 grain bullets, IMO. If you substituted A2200 powder, for example - a full case of about 30 grains - you would get close to 2850 fps in your 16" barrel without resorting to compressed loads. - CW

Post Toastie
10-16-2013, 06:54 PM
Thanks luvmymini14 and CW for the replies. Looks like I'll stick with AA2200 for 6.8.

gtfoxy
10-17-2013, 11:24 AM
Anyone tried 130grn Hornady Interlocks w/ 8208?

I will be loading up 120 SST's & 130 Interlocks 2day. Hopefully will get a decent day soon to test groupings.

sgt. mike
10-17-2013, 12:49 PM
The best group I've ever shot out of my SOTA 16" spec 2, 1:11 upper was with with 29 gr. 8208 under 120 gr. sst's in hornady brass, F205 M primers, 2.255" COAL. 3 shots in 1 ragged hole @ 100 yds. Velocity was a sedate 2415 fps. & primers were very flat. I've since gone to AA2200 for all my 6.8 loads as it's easier to get max charges in the case without compression, but that 3-shot target w/ 8208 is stuck to my fridge w/ a magnet for the warm fuzzies I get whenever I look at it.

gtfoxy
10-17-2013, 10:07 PM
The best group I've ever shot out of my SOTA 16" spec 2, 1:11 upper was with with 29 gr. 8208 under 120 gr. sst's in hornady brass, F205 M primers, 2.255" COAL. 3 shots in 1 ragged hole @ 100 yds. Velocity was a sedate 2415 fps. & primers were very flat. I've since gone to AA2200 for all my 6.8 loads as it's easier to get max charges in the case without compression, but that 3-shot target w/ 8208 is stuck to my fridge w/ a magnet for the warm fuzzies I get whenever I look at it.

Interesting, thank you.

What is your velocity & groupings now with your "go-to" 2200 load with the SST's?

Benchrest Hero
03-14-2014, 08:53 AM
I've been wanting to experiment with 8208 since i have an abundance of it lying around for my bench rifles but couldn't find anywhere that seemed think it was a viable powder rate for the 6.8. Glad to see Someone tried it

Soonlobo
03-14-2014, 10:28 AM
IMR 8208 XBR works very well with 130 SST's and 130 Nosler BT's. 28.4 grains loaded with drop tube in twice fired SSA brass COAL 2.4" and 2.425" in open magazines and shaved magazine well. No chronometer data. Less than MOA accuracy from 18" Wilson Combat SPC II barrel. Slight signs of pressure.

ShannonGTO
03-14-2014, 06:07 PM
Wow my 2500fps with a 110Barnes XXX seem like a pellet gun to this and I was proud of myself...

AKsarben
03-17-2014, 10:44 PM
Other powders will give better fps, no doubt. However, the 29.5 grain I use on the 120gr Hornadys gets a pretty nice group, no excessive pressure signs. I am no engineer on this, but it seems as much as it is compressed that this might effect the burn rate and increase the burn rate as the bullet travels down the barrel. Makes the action function without a hitch and kills coyotes out at 300+ yards.