6.8 Spc, or 6.8 Spc II, or ?

[Prov 18:19]

Re: 6.8 Spc, or 6.8 Spc II, or ?

Is it possible to shoot subsonic 6.8 in a 1-11 twist 20" barrel and reliably cycle the bolt?

 

[rsilvers]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Proverbs 18:19</div><div class="ubbcode-body">Is it possible to shoot subsonic 6.8 in a 1-11 twist 20" barrel and reliably cycle the bolt? </div></div>

Yes, if it is 200 grains, but it won't be stable unless you have 1/7 twist.

 

[bustin]

Re: 6.8 Spc, or 6.8 Spc II, or ?

A 20" barrel has a rifle gas system the port is too far from the chamber so the pressure drops low just like it would with a 300BLK thats why most BLKs have carbine and pistol gas systems.
So no, but then why would you want to shoot subs out a a barrel designed to get more vel by being longer?

 

[Prov 18:19]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">A 20" barrel has a rifle gas system the port is too far from the chamber so the pressure drops low just like it would with a 300BLK thats why most BLKs have carbine and pistol gas systems.
So no, but then why would you want to shoot subs out a a barrel designed to get more vel by being longer? </div></div>

Things change.

So what would be a solution short of going SBR?

 

[rsilvers]

Re: 6.8 Spc, or 6.8 Spc II, or ?

Use a 16 inch.

 

[Powder_Burns]

Re: 6.8 Spc, or 6.8 Spc II, or ?

200gr .277 dia is pretty much vaporware, unless you know something I don't. That being said you can't compare the merits of a cartridge designed from the ground up for subsonic use (300 Whisper) to one intended to run supersonic ammo to improve barrier penetration capabilities over the 5.56mm. They are different tools in the shed so to speak.
However I am interested in learning why a 110 TSX at 2100fps out of a fast twist 300BLK has more terminal effect than a 110 TSX at 2800fps out of a slow twist 6.8 SPC.

 

[bustin]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Proverbs 18:19</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">A 20" barrel has a rifle gas system the port is too far from the chamber so the pressure drops low just like it would with a 300BLK thats why most BLKs have carbine and pistol gas systems.
So no, but then why would you want to shoot subs out a a barrel designed to get more vel by being longer? </div></div>

Things change.

So what would be a solution short of going SBR? </div></div>
if you want to shoot subs use a carbine length gas system on a 16" barrel
And if talking about a 6.8 buy one of the 9.5 twist model 1 sales barrels that everyone is giving away, sub use is the only thing they are good for.

 

[rsilvers]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Powder Burns</div><div class="ubbcode-body">However I am interested in learning why a 110 TSX at 2100fps out of a fast twist 300BLK has more terminal effect than a 110 TSX at 2800fps out of a slow twist 6.8 SPC. </div></div>

The actual velocities are 2400 fps for a 110 in 300 BLK 16 inch barrel, and 2550 fps for a 110 TSX from 6.8:

http://www.ssarmory.com/6.8_spc_ammo-2-1-1-2.aspx

I am not sure which has better terminal effects. The 300 BLK will make a larger hole and still penetrate 20 inches. Six of one, half dozen of the other.

 

[bustin]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body">I know you don't. You built your company around 6.8. It is what you do.

5.56mm - I would not be without one - I like having what the military has.
</div></div>
Actually the 5.56 is the best logical choice for training, SD/3 gun/combat for many reasons. The 6.8 is the best hunting round that will fit in a AR15 and is widely avail to the common Joe. I shoot a 6.5BRX out of a AR15 but I can make what ever I want.
In the end I believe we will sell only the 5.56, 6.8 and 308 for very obvious reasons.

 

[rsilvers]

Re: 6.8 Spc, or 6.8 Spc II, or ?

You can say things about 300 BLK to try to talk people out of it, but the fact that it is 30 cal, works in normal mags without losing capacity, and has a low price - it is going to be attractive to a lot of people. Ultimately, it is hard to compete with what it offers combined and a low price. I know how important price is, and I will work to keep it low and moving downward.

 

[Prov 18:19]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Proverbs 18:19</div><div class="ubbcode-body">Is it possible to shoot subsonic 6.8 in a 1-11 twist 20" barrel and reliably cycle the bolt? </div></div>

Yes, if it is 200 grains, but it won't be stable unless you have 1/7 twist. </div></div>

Accuracy will obviously suffer but at short ranges that's not a problem. On the plus side the tumbling round will offset the lack of expansion due to the slow speed of a subsonic. My concern is that the round may be unstable enough to cause a baffle strike.

 

[rsilvers]

Re: 6.8 Spc, or 6.8 Spc II, or ?

Accuracy may or may not suffer - but if it does, I don't think it is obvious. It simply needs to be tested.

 

[lwrkeysfisher]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Powder Burns</div><div class="ubbcode-body">However I am interested in learning why a 110 TSX at 2100fps out of a fast twist 300BLK has more terminal effect than a 110 TSX at 2800fps out of a slow twist 6.8 SPC. </div></div>

The actual velocities are 2400 fps for a 110 in 300 BLK 16 inch barrel, and 2550 fps for a 110 TSX from 6.8:

http://www.ssarmory.com/6.8_spc_ammo-2-1-1-2.aspx

I am not sure which has better terminal effects. The 300 BLK will make a larger hole and still penetrate 20 inches. Six of one, half dozen of the other. </div></div>

What is the velocity of factory loaded 110t-tsx from a 16" 300Blk? Certainly not 2400fps? Wasn't it losing petals at that velocity?

See here.

 

[Prov 18:19]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body">Accuracy may or may not suffer - but if it does, I don't think it is obvious. It simply needs to be tested.</div></div>

granted. but we are on a forum dominated by precision shooters. just sayin.

 

[bustin]

Re: 6.8 Spc, or 6.8 Spc II, or ?

SSAs 6.8 commercial loads may hit 2550 in some, 2600 in better barrels. The Tac load is apx 50 fps faster. Up until 2009 SSAs 110gr bullets were doing about 2700 but they were downloaded to work better in some rifles that didn't have the best specs. Hornadys 110s hit 2600fps from our 5R barrels. Handloaded 110s can reach 2750+ pretty easy.

 

[rsilvers]

Re: 6.8 Spc, or 6.8 Spc II, or ?


Tighter chambers produce more velocity for any given ammo.

 

[bustin]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body">
Tighter chambers produce more velocity for any given ammo.
</div></div>
Funny ours are larger but the rifling specs are 5R and the bore area is different. So since you have never had one of our barrels in your hands tell me why ours are faster.

 

[rsilvers]

Re: 6.8 Spc, or 6.8 Spc II, or ?

I don't know. First I would have to establish that it is faster than a SAAMI test barrel, then I would look at the chamber and bore area to find out why.

 

[Prov 18:19]

Re: 6.8 Spc, or 6.8 Spc II, or ?

is there any excessive wear and tear on the 6.8 rifle caused by subsonic rounds that fail to cycle the action?

 

[Powder_Burns]

Re: 6.8 Spc, or 6.8 Spc II, or ?

You could pinch off a gas tube and turn any DI gun into a single shot. I don't think its going to break the gun.

 

[Prov 18:19]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Powder Burns</div><div class="ubbcode-body">You could pinch off a gas tube and turn any DI gun into a single shot. I don't think its going to break the gun. </div></div>

Can you install a valve to manually open or close the gas tube without causing any damage to the rifle?

 

[Powder_Burns]

Re: 6.8 Spc, or 6.8 Spc II, or ?

Adjustable gas block.

 

[Prov 18:19]

Re: 6.8 Spc, or 6.8 Spc II, or ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Powder Burns</div><div class="ubbcode-body">Adjustable gas block.</div></div>

roger that