Muzzle Velocity from 6.8SPC rifles and POF 9.25" SBR

P

Predator Popper

New member
I tried finding real information on MV from 6.8SPC rifles and 6.8SPC SBR's.. Never found what I was looking for. So, this morning I went and got some data for everyone.

Muzzle Velocities

POF 9.25" SBR 6.8SPC

SSA 85 Grain TSX
2834, 2782, 2894, 2898... WOW

31.0 Grains Benchmark with 85 grain TSX
2561, 2532, 2538

28.8 Grains Benchmark with 110 Sierra HP and TSX
2310, 2340, 2371, 2340

16" POF 6.8 SPC

31.0 Grains Benchmark with 85 grain TSX
2947, 2998, 2963

SSA 85 Grain TSX
3247, 3279, 3234

28.80 Grains Benchmark with 110 Sierra and TSX
2625, 2632, 2629

Thompson Encore with 18" Barrel

31.0 Grains Benchmark with 85 grain TSX
2817, 2863, 2864

SSA 85 TSX
3240, 3220, 3361

28.80 Grains Benchmark with 110 Sierra and TSX
2693, 2621, 2607

Now, by looking at the data, the Silver State Armory (SSA) loads whoop my reloads, BUT I had some problems with it. First, I had to consistent FTF's (30%-40%!) ONLY with the SSA. I had to double stike most and one did not fire at all! There is clearly a problem with this lot of ammo. There were no problems with reloads what so ever.

No doubt, the SSA's are much hotter. You can tell from the "report". The 9.25" SBR REALLY surprised me. Loaded with SSA ammo, it was almost as fast as my reloads from a 16" barrel. The MV between the 16" and 18" barrels, the 16" barrel was faster! I must say the Thompson Barrel is a 1:10 twist and the POF is 1:11 and chambered differently. That may make sense when you take into account the 6.8SPC was designed with a 16" carbine in mind.

I should note, today, I did not shoot for accuracy. I personally have had problems with the SSA grouping in the past. That was the reason for my reloads. With my own loads, I consistently shoot < 1 MOA. Today was simply for MV. Wind was too bad.. Tonight, I will shoot for groups if the weather cooperates.

My philisophy is you can't kill what you can't hit... All the coyotes taken with the 6.8SPC reloads were DRT.... No running or spinning, just dead... I know there are MV junkies out there. I though I would share some intel with everyone. I just though you guys may find the results interesting. I know I did!
 
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Predator Popper,
Did you Chrono any other "Factory" loads in your short 6.8?

I am interested in the 9.25" SBR; I will get a SureFire can for mine, after the tax stamp arrives.

Karl in Phoenix
 
Popper, have you tried Reloader 7 or H4198 with the Barnes 85 grain bullets? Some of the guys on 68forums use those powders for lighter bullets with good velocities and accuracy.
When my new Bison Armory barrel gets here I'm going to try Reloader 7 to see if I can reach 3000fps with the 85 grain bullet.
 
good info, nice to know since ill be getting a 10" contender barrel delivered any day now.

Thanks for posting

Dave
 
No I have not tried those powders. Once
you try a load, let me know what results you get. I'm interested
smile.gif


I did find out done information on the SSA ammunition. They use military primers which are harder than commercial primers. You have to change the hammer springs in some rifles to hit the primer hard enough. Don't like that at all....
 
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Just received an email for Art at SIlver
State Armory, this is the response,

"We only use Mil-Spec primers (You can read between the lines why we use these primers) and other do not. These primers require a hammer spring of 4.5 pounds and the firing pin must patrude .029 -.030 from the bolt face. The reason for the harder primers is to insure the weapon does not go into full auto while in semi mode. An AR has a free floating firing pin which will tap the primer each time a round is chambered and a thin base primer may go off while your finger is off the trigger, also TC'S all have a light hammer spring. In 5.56 you can get away from a Mil-Spec primer because the action is less intense than that of the 6.8. 
 
But that does not solve the issue at hand and I do know how you feel at the range when things go wrong, but I also know how it feels when a weapon goes full auto and you do not expect it. Here's what we can do, you can keep the ammo (more costly to return it) and we will send you replacements at no charge with commercial primers, this will solve the non-firing issue in your weapon. In the future when ordering from us please check the box asking for commercial primers this will obsolve us from any liablity if your weapon goes full auto (recent new feature). Also some shooters feel a need for a fancy trigger group for their assualt weapon, these trigger assemblies have a light hammer spring, a case in point "Timney triggers". My understanding is Timney has and will replace the hammer spring for a small charge and this will also fix the issue with their assembles. At some point in time you may want to look into the hammer spring and firing pin.
 
I have CC'd Nancy on this email, please write her and she will handle things for you.
 
Best regards
 
Art - SSA"

It appears to be the TC and the Timney in the POF causing my issues. I will have new springs installed and let you guys know if that works. I can say, SSA has went above and beyond helping me resolve these issues. I really hope it does work. The difference of 400fps is MUCH faster than my loads! Speed means energy AND a flatter trajectory! They are sending me some with commercial primers. I will let eveyone here and 68forums know how accurate they are from the SBR.... I did shoot some lately, one at a time.... and got great results! That surprised me...I am hitting consistently 3" at 200 yards with a POF SBR, Aimpoint CompM4, and 3X magnifier! That is not bad! The red
dot is 2" MOA. I will put a scope on it and give one more update...
 
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From what I know from my dealings with SSA, if you own a
6.8 SPC, you want to do business with SSA. Their brass is
the highest quality 6.8 SPC brass on the market. Their ammo
is top shelf, and they go to great pains to offer different
flavors to span the spectrum of 6.8 SPC barrel rifling twist
rates, and chamber reamers. I also have a wildcat 6mm WOA,
which is based on the 6.8 SPC case. It only sees SSA brass.
Before I knew better, I purchased a couple hundred pieces of
Remington brass. That will never happen again. It will
get used up as hunting ammo, where brass disappears. I have a
few life times of SSA brass stashed.
grin.gif


SSA is a great example of a vendor that goes the extra mile
to offer their customers quality products, at a competitive
price, and I hope that never changes.

Squeeze
 
I will echo what was posted above in regards to SSA.

First rate people and the only folks I buy 6.8 ammo from. They are big supporters of the trigger pullers on the ground in the middle east.
 

You may want to try hand loads with Sierra 90 gr. HPs. A less
expensive alternative to the 85 TSX, unless the target is deer
sized game or hogs. The 90 gr. HPs are very accurate in
my 16" 6.8mm. I haven't chronographed the load, because
I loaded to an accuracy node, but from the range tests, it
is still climbing at 150 yards. So it appears pretty flat
out to Wisconsin coyote ranges. I think SSA also loads this
bullet. They may call it OTM(Open Tip Match) ammo.

Alliant 10x is also a good powder for 110 gr. bullets. Seems
to be a good choice for MV and accuracy.

Another way to squeeze a bit more MV out of the loads is use
brass with LR primer pockets. I suspect SR Magnum primers
may help a bit more, for small pocket brass. Back the
loads down a couple of grains, and work back up, if you
switch to magnum primers.

Squeeze
 
The SSA ammo with 90 grain bullets run great in my LWRC........ They are a keeper.... Thank you Art!!!!!!! My daughter took a 4x4 Coues with the 6.8spc it was a Barnes X 85 grain...... One shot and a bang flop.......
 
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