Anybody still shoot 6.8?

[Bubba FAL]

Bought my first 6.8 in 2004, a 16" CMMG. Nearly blew it up with that early SSA ammo. Followed a year or two later by an 18" Ko-Tonics. Shot Highpower matches on and off with it. Built a 3rd 6.8 in 2016 - another 18" , this one is a Bison Recon profile on an Aero Precision receiver set.

Still have all three, still shoot 'em.

[AndyLate]

Reviving an older thread to ask a question. Is an adjustable gas block required for a 6.8? Specifically a 16" ARP Scout 6.8 SPC II using factory loads or handloaded equivalent?

Thanks

Andy

[454308]

No arp barrels run fine without agb when not suppressed. If you plan to suppress it then an agb and heavier buffer are needed.

Sent from my SM-G973U using Tapatalk

[diving dave]

I agree with 454308, my 16 inch arp runs great without the can, but very overpassed with it. (AAC 762SD) I added a Bootleg carrier and she runs great now.

[fledge]

Reviving an older thread to ask a question. Is an adjustable gas block required for a 6.8? Specifically a 16" ARP Scout 6.8 SPC II using factory loads or handloaded equivalent?

Thanks

Andy

Depends on when ARP opened up the gas port on the one you’ll acquire. Seems 18 months ago, ARP recommended a carbine buffer. The barrels were soft shooting and better with cans. After complaints of undergassing, ARP opened them up (per a thread on 68forums). I’m sure you can find the sweet spot with the right buffer. If you want a 12.5 too, I have one available.

[ColtSeavers]

Still shooting my 18" DD Nitride S2W (yep, they were nitride originally) 6.8.

[BillB]

Fledge, I might be interested in that 12.5". 5R? 3R? If you want to expound I'll listen

[AndyLate]

Depends on when ARP opened up the gas port on the one you’ll acquire. Seems 18 months ago, ARP recommended a carbine buffer. The barrels were soft shooting and better with cans. After complaints of undergassing, ARP opened them up (per a thread on 68forums). I’m sure you can find the sweet spot with the right buffer. If you want a 12.5 too, I have one available.

It will be a new production barrel. I'm seriously thinking of taking advantage of the seller's market and greatly downsizing my firearms collection. If I pull that off, then having one nice lower with 16" rimfire, 5.56, and medium game uppers is atractive to me. I already have the lower, rimfire, and 5.56 uppers.

Full disclosure - I have a lot of ideas, they don't all come to fruition.

Andy

[constructor]

It will be a new production barrel. I'm seriously thinking of taking advantage of the seller's market and greatly downsizing my firearms collection. If I pull that off, then having one nice lower with 16" rimfire, 5.56, and medium game uppers is atractive to me. I already have the lower, rimfire, and 5.56 uppers.

Full disclosure - I have a lot of ideas, they don't all come to fruition.

Andy

If you know what size you want the port write it in the additional comment box. I can port it any size you want it.
My personal barrels have a .078 or .082 port but I run hot handloads and have no gas leaks. If you shoot Hornady at 54000psi and have no leaks a .082 will work. If you shoot weaker Remington and Nosler/SSA you may need a .086. If you don't seal the gas leaks and shoot Remington you may need a .089.

[Disciple]

These were taken from Brassfetcher and seem to correlate with the US military's testing in terms of 6.8 calibers producing better wounding than even 6.5 when passing through barriers:
Attachment 61306
Attachment 61307
Attachment 61308

Testing from multiple sources confirms this phenomenon. One would not think 0.3mm in diameter matters, but it seems to be the threshold where the increase in fluid drag is just enough provide better terminal performance on average. It's a trade off in slightly more KE / velocity loss at longer ranges vs. 6.5mm projectiles.

What is the y axis? Energy per unit distance? Energy per unit time?