Personal Experiences with SSA 90g TNT factory loads Short Stroking...?

[owenslee]

We all appreciate that SSA makes premier 6.8 SPC ammo.

Personally...I love their 110g Pro Hunters and use it more than any other round for hunting and range use.

However...I have now had four separate weapons of different configurations / manufacturers which have not been able to shoot the SSA 90g TNT round reliably.

Each weapon has used the standard carbine buffer and standard carbine buffer spring.
Each weapon has used standard weight AR15 bolt carriers.

Barrels / uppers used have included two Cardinal uppers in 20" and 16", one Xtreme 16" and one Rock River Arms 16".

One weapon could fire three to four rounds before short stroking. The other three would short stroke on every round.

I could then switch to off the shelf SSA 110 Pro Hunters and all weapons cycled flawlessly without a glitch of any kind.

At the 68Forums Match...the SSA 90g TNT round was the ammunition supplied by SSA in a drop shipment for shooters that did not bring their own ammo. During the match there were multiple shooters who had short stroking issues, but I did not document which shooters had the problem, and of those which were having the problem with the SSA 90G TNT round.

I am going to call Nancy and /or Art in about a week to discuss this issue and wanted to open up a thread to determine how many shooters on the forum have experienced short stroking ONLY with the SSA factory loaded 90g TNT ammunition.

If you have experienced an issue PERSONALLY...(not here say from what one of your buddies expereinced)...please provide details of your upper / barrel/ bolt carrier/ buffer and buffer spring.
Based on your responses, I want to provide the details to Art when I call.

Keep the information factual and objective. We want this to be helpful information for Art... This is also not going to be a SSA bashing thread.

If issues with ANY other round is added to this thread...SSA or otherwise...I will delete it. ONLY data regarding the SSA 90g TNT factory loaded ammunition should be included here.

If you have been running the SSA 90g TNT without any issues...I especially want to hear from you and learn the details of your weapon.

Also...try to gage the age of any of the subject ammo you have been shooting either with or without problems. Perhaps it is an issue with a particular batch or time frame and knowing when the ammo was made will help to isolate the problem.

Thanks for your input.

Kerry

[joshuades]

For the sake of clarity, the issues I had were also during tuning my rifle when all the rounds were short stroking. Those issues turned out to be my buffer was too heavy and it had secondary springs which were too tough to compress at the end of the cycle. The buffer issues have been fixed but I haven't been able to get out to shoot again yet. The severity of the short stroking issues, though, were effected by the ammo type I was shooting.

At that point in time, the lot of 110PH I had would cycle the action and load another cartridge, but not lock back on the last round. The 90TNTs would not cycle the action far enough to load another round during the same session. The PH were old combat loaded pressures and the TNTs were from a batch I ordered in late Jan early Feb of this year.

The regular short stroking issue at the time was the secondary springs in the buffer were too stiff to be compressed by any normal load in the rifle, causing it to not lock back on the last round. Of the rounds I tested, the TNT evidenced more severe short stroking than the others. the others, though, are old combat loadings.

The weapon set up was with a Young Mfg. NM BCG, an MGI rate reducing buffer (which at the time was modified by removing all the weights and replacing them with delrin spacers to hold the secondary springs in their places, weight at 2oz), standard buffer spring. Barrel is an AR Performance 18", midlegnth Pac Nor 1:12 3groove.

[zoomie]

I don't have a huge sample size, but I've fired a couple boxes (~50 rounds) of the 90gr TNT and never had a cycling issue of any sort.

PRI mags
WOA 1:11 SPCII 16"
Rifle buffer, standard spring, commercial buffer tube
Purchased the ammo last fall

[owenslee]

I don't have a huge sample size, but I've fired a couple boxes (~50 rounds) of the 90gr TNT and never had a cycling issue of any sort.

PRI mags
WOA 1:11 SPCII 16"
Rifle buffer, standard spring, commercial buffer tube
Purchased the ammo last fall

Brian...I'm assuming your running a full length rifle stock...correct?
What weight or type of bolt carrier?

Kerry

[zoomie]

Correct, A2 length (ACE skeleton) stock.

Bolt carrier is standard carrier from White Oak. Not a Young or anything special. I think he uses a lot of Stag parts, but can't tell you my actual brand.

[Zippy]

I had quite a few issues with the 90 gr TNT at the training in NC using several uppers.

[owenslee]

I had quite a few issues with the 90 gr TNT at the training in NC using several uppers.

What weapon details can you provide for those that would not cycle...?
Particularly barrel / buffer/spring and bolt carrier details

Kerry

[Zippy]

What weapon details can you provide for those that would not cycle...?
Particularly barrel / buffer/spring and bolt carrier details

Kerry
Well, the Addax GPU with 16" barrel / standard buffer / standard spring / National Match carrier on an Anvil Arms lower. That upper was brand spanking new. I sent Chris from Addax 80 rounds of the ammo he should be receiving soon so he might have feedback of interest also.

There was the POF one I used but I don't have the details on that one. It was also brand new There was also the one I borrowed from Jason but I don't remember the details on that one either.

[marinesg1012]

I had issues feeding the 90's till I tweaked my feed lips, I didnt shoot much of the 90's after that becuase they were none combat and they didnt seem to cycle well but I honestly cant remember.... with the 85's expecially the new none tac loading I had to open my gas port and trim the spring to get them to reliably cycle....

[maggiepi]

The 90 TNT ran smooth in my carbine and seemed OK in my mid-length.

MS

[owenslee]

Guys...this thread is not about issues with Pro Hunters or any round OTHER than issues with the SSA 90g TNT.

Note in the original post:

If issues with ANY other round is added to this thread...SSA or otherwise...I will delete it. ONLY data regarding the SSA 90g TNT factory loaded ammunition should be included here.

Please stay on topic...

Kerry

[kalwasart]

We went thru our normal checks on a new powder that we started to use on the 90 grain TNT's. Everything looked fine thru ballistic's and thru several weapons. We loaded a couple of thousand and sent some of them out. The next day we put them thru a battery of weapons (12 in all) from 8 inchers to 20 inchers both DI'S and pistons.

We found that several weapons were having issues with short stroking. We stopped loading and pulled the item off the web. Since then we have been waiting on the replacement powder to arrive (months now). We are sitting on 100's of thousand of projectiles all this time. What this also shows us is the differences you see between weapon systems.


Art - SSA

[owenslee]

Thanks for the update Art.

I had hoped we might have some additional input to add before I called you. It's encouraging to know you have already identified a problem and have a fix pending.

Let us know when those of us with the affected ammo can return it for replacement.

Would it be possible to return the affected 90g TNT's we received at the 68Forums match for an alternate round such as the Pro Hunters? Especially those of us who do not normally shoot the 90g TNT but only bought it because it was the only SSA round offered in the bulk shipment for the match.

Please advise.

Thanks.

Kerry

[constructor]

For the sake of clarity, the issues I had were also during tuning my rifle when all the rounds were short stroking. Those issues turned out to be my buffer was too heavy and it had secondary springs which were too tough to compress at the end of the cycle. The buffer issues have been fixed but I haven't been able to get out to shoot again yet. The severity of the short stroking issues, though, were effected by the ammo type I was shooting.

At that point in time, the lot of 110PH I had would cycle the action and load another cartridge, but not lock back on the last round. The 90TNTs would not cycle the action far enough to load another round during the same session. The PH were old combat loaded pressures and the TNTs were from a batch I ordered in late Jan early Feb of this year.

The regular short stroking issue at the time was the secondary springs in the buffer were too stiff to be compressed by any normal load in the rifle, causing it to not lock back on the last round. Of the rounds I tested, the TNT evidenced more severe short stroking than the others. the others, though, are old combat loadings.

The weapon set up was with a Young Mfg. NM BCG, an MGI rate reducing buffer (which at the time was modified by removing all the weights and replacing them with delrin spacers to hold the secondary springs in their places, weight at 2oz), standard buffer spring. Barrel is an AR Performance 18", midlegnth Pac Nor 1:12 3groove.

Did you open the port to .093? I have changed port sizes on the mid length gas due to lower pressures in 12x3 and XT barrels.
Just saying if possible everyone should check their port sizes and enlarge to .093 if SS is a problem with mid length gas systems. All XTs have .093 ports.

[dark1]

I was running the 90gr rnds in my stag mod 5 at the match. I was not having short stroking problems but i could tell the rounds were to weakly loaded they had about 5% less recoil than the ProHunters i was running. For some resin the bolt was unlocking early venting gass down in to the mag burnishing the ammo left in the mag the the theory at the match was was it was doing this because how light it was loaded the bolt was unlocking before the powder was finished burning. I still have 100 rnds of the ammo but all iam going to use it for is plinking i do not trust it fore any thing elts.

[LKirchoff68]

I had some issues with the 90gr TNT's I had as well, even though I guess my input is a little late. I only bought 2 boxes in about late January early February. One box functioned just fine, but I experienced short stroking with about 5 rounds with the other box.

I have a 1:9.5 twist mid-length Kotonics, Young's NM M16 carrier, A2 stock, and a regular rifle buffer and spring. Was using a CP mag that had never failed before or since.

[kalwasart]

Constructor is correct, the slower twist can and may cause problems. Our 90 and 85 grainers use a fast burning powder, the combination of twist and a light projectile makes things intertesting. Correct me if I am wrong constructor but the weapon I have is correct to what you are now using? I need a pressure barrel in this configuration to run it thru our computerized system to see what pressures it is running at. If you can get it made I will send you drawings of the barrel (outside dim's) just let me know the cost.

For accuracy the 90 grain TNT from our test stand shots a consistant sub 1/2 MOA.

For those having problems are you shooting a DI or piston system. It appears that pistom system handles the lighter loads better, but we will know more when we get the powder in.


Art - SSA

[owenslee]

For those having problems are you shooting a DI or piston system. It appears that piston system handles the lighter loads better, but we will know more when we get the powder in.


Art - SSA

Art,

All four of the weapons I have tested that short stroked were Direct Impingement uppers.
Thats 100%...I have yet to shoot a 6.8 that has not had an issue with the 90g TNT load. I don't own or plan to own a piston upper...other than a Daewoo 6.8 SPC project down the road.

Since there are FAR more DI uppers on the market...I would be concerned about any round that is unreliable in a notable percentage of DI systems.

Kerry

[marinesg1012]

Art I would pay for a preassure tested barrel from H if we could get ammo designed for those barrels.....

[Zippy]

Constructor is correct, the slower twist can and may cause problems. Our 90 and 85 grainers use a fast burning powder, the combination of twist and a light projectile makes things intertesting. Correct me if I am wrong constructor but the weapon I have is correct to what you are now using? I need a pressure barrel in this configuration to run it thru our computerized system to see what pressures it is running at. If you can get it made I will send you drawings of the barrel (outside dim's) just let me know the cost.

For accuracy the 90 grain TNT from our test stand shots a consistant sub 1/2 MOA.

For those having problems are you shooting a DI or piston system. It appears that pistom system handles the lighter loads better, but we will know more when we get the powder in.


Art - SSA

The Addax GPU I had issues using was a piston upper.

[joshuades]

Did you open the port to .093? I have changed port sizes on the mid length gas due to lower pressures in 12x3 and XT barrels.
Just saying if possible everyone should check their port sizes and enlarge to .093 if SS is a problem with mid length gas systems. All XTs have .093 ports.
I've yet to open it up. I have put lighter internals in it to shed weight, so that works about the same. If I remember right, the old ports are around .083 or .087? I don't intend on changing it unless I really, really have to.

I had to put lighter springs in the buffer to make it compressable and now it locks back (the original problem of the short stroking). I could probably put one of the weights back in it and it still would work alright. Right now the buffer is just shy of 2oz.

The TNTs don't bother me as I just use them to test function and confirm zero. Knowing how they work I can gauge how the hotter loads will perform. Right now the TNTs eject but they don't feed another round, at that point the hotter loads will function right. If I set it up where the TNTs run the action right, the hotter loads would bash buffer into the back.

[constructor]

Constructor is correct, the slower twist can and may cause problems. Our 90 and 85 grainers use a fast burning powder, the combination of twist and a light projectile makes things intertesting. Correct me if I am wrong constructor but the weapon I have is correct to what you are now using? I need a pressure barrel in this configuration to run it thru our computerized system to see what pressures it is running at. If you can get it made I will send you drawings of the barrel (outside dim's) just let me know the cost.

For accuracy the 90 grain TNT from our test stand shots a consistant sub 1/2 MOA.

For those having problems are you shooting a DI or piston system. It appears that pistom system handles the lighter loads better, but we will know more when we get the powder in.


Art - SSA

I will talk to the barrel manufacturer this week about building a test barrel when he runs my other batch.

[kalwasart]

DI' system can and will have more problems with the lighter projectile and more so if it has a slow twist rate. I have shot several hundred rounds thru piston sytems and all funtioned fine because the operating pressure is higher on a pistom system.

Now that you all think i'm nuts, at the port of a piston system the pressure turns into mechanical energy at the gas block to release the bolt. In a DI system the gases must travel down the gas tube into the bolt carrier group before it turns into mechanical energy to open the bolt. As the gas travels to the carrier the pressurer is dropping.

Only two thousand rounds lift here, how many went to pistom system we do not know. If you have a problem with the 90 grain TNT send me a PM.

As I mentioned earlier we are sitting on hundred of thousands of projectile waiting on powder. I personelly love the 90 grain TNT it is very accurate and with the right powder its smoken.


Art

[marinesg1012]

I hope that new powder shows up soon, I want to see what you guys can do with the 85's and the 90's :D

Keep up the good work Art you know we all appreciate all the work you do for us... and we show it by sending you a good percentage of our checks :D

[Addax Tactical]

Did you open the port to .093? I have changed port sizes on the mid length gas due to lower pressures in 12x3 and XT barrels.
Just saying if possible everyone should check their port sizes and enlarge to .093 if SS is a problem with mid length gas systems. All XTs have .093 ports.

The same here with my Mid-Length 6.8 GPU's.

I just tested a couple of rounds of the 90 grain TNT, and short stroked.

The rounds felt soft and weak.

I popped in a couple rounds of 110 grain hunter, and the GPU cycled with no issues.

I am going to open up the gas port hole just a tiny bit more on my test rig (no more than .960) and see how the GPU cycles with the 90 Grain TNT I have.

[ron169]

I purchased 5 boxes of the TNT ammo when yall had the limited availibility that was mentioned above. I have yet to test them yet because I havent gotten my Xtreme upper, but even if they dont function, I plan to use them to break my upper in, so no worries to me if they are under powered. Ive got no problem single loading them

[snaz567]

No Problems here.

[snaz567]

We are sitting on 100's of thousand of projectiles all this time.
Art - SSA

Well I'll take a thousand of those then. lol.

I had no problems in my 12.5" carbine gas. Standard buffer and spring.

[moose-hunter]

I took a peek at my ammo "stash" and found 100 rounds of what's labeled as "90gr SSA PLINKING". No mention of tactical or commercial loading. Is this the same round as the TNT's in question? The bar code number on all five boxes is 04879 14776.

I've hand loaded using the 90gr TNT but ran them quite hot with no issues in either of my rifles. But if these factory rounds are "low powered".... With the heavy carriers in my guns I can almost bet the factory rounds will short stroke.

One has a 12.5", 1:11 WOA (6 groove ?) barrel, DMR chamber, Young M16 National Match Carrier, LMT bolt, standard carbine buffer and spring.

The other a is 18" AR Performance Super Match (4 groove?), 1:11, DMR chamber, Young M16 National Match Carrier, LMT bolt, "H" buffer and a standard carbine spring.

My schedule is locked down for quite a while with zero chance of any range time or I'd fire off a box or two for testing... What should I do with these rounds? Can they be exchanged for my all time favorite, the 110 PH tactical loads?

[LEO-Nidas]

I have had no short stroking with my box.
My rifle is configured as follows:
16" Cardinal Armory 1in11 SPC2 (midlength of course)
Carbine buffer


I do not rapid fire with this round. I only use this round to slay ground hogs. It works quite well and is very accurate. I have killed 3 in the past month. With every shot I take, the rifle cycles and and loads a new round with no malfunctions to date. I previously had zeroed my rifle with pro hunters. I attached some pics of results.