I have found lots of information on the web concerning the velocities of both these rounds out of 16'' barrels, and even more on the ubiquitious 10.5 inch 5.56 (needs to fire heavier rounds out of a faster twist barrel for more fragmentation range) which at best with mk 262 mod 0 has around a 100 meter fragmentation range. But I can't seem to find this data for a 10.5 inch 6.8 barrel. I have seen many in the 12" range but only one 10.5" that John Noveske makes. My question is whether the fragmentation range will still be greater in the  6.8 if it is shot from a 10.5 inch barrel, or will it just burn up too much powder to be anymore effective than 5.56 shot out of the same length barrel using mk262 mod0? Any help would be greatly appreciated, also not to start two topics at once, but does anyone besides OPS Inc. make a suppressor for this (6.8 SPC) caliber? And when running a suppressor on either caliber at the 10.5 inch barrel length, is an adjustable gas block needed to help regulate the back pressure, or is it not that big of a deal if you're not running it full auto? The reason I ask is because I would like to be able to shoot it with and without the suppressor attached, so the other idea I had instaed of the adjustable gasblock would just be a KX3. Any knowledgeable input would be great, thanks guys, I know it's a big question.

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The Leitner-Wise 6.8SPC gas-piston carbines chrono 2,400fps from 10.5in barrels with Silver State Ammo. The Remington fodder is 150fps slower. 6.8 SPC OTM fragments down to around 2,100fps, which gives the SBR 6.8 an effective frag distance of >150 yards. If you are running non LOLW compliant projos, it's even better.....

6.8 is optimal in 10.5-16inch barrels, beyond which you're getting next to nothing in Mv gain. When stacked against Mk262, it has substantially more energy and lethality (larger bullet fragmenting)

The LW piston is self-regulating so we don't bother with an adjustable block.


This is 48th Highlander's 6.8 SRT-10.5 (Calibre/Configuration/Barrel length)

It's got a low-profile gas block under the ARM-R midlength rail.

On the muzzle is an AAC QD 'star' mount  for their M4-2000 and SCAR-SD cans, both of which are available in 6.8.


48th Highlander(left) is hodling our Super 6.8 tech demonstrator with the custom 6.8 can we commissioned from Jet. It telescopes back over a mount turned directly onto the barrel. Tres cool and very quiet too.

Simon

Thanks for the info simontan, but what about parts that are actually available to the public now, not some piston system that has over a year of back orders on it. I like the idea of a piston, but from what i've read so far, reliability is really better with direct gas impingement anyway. So I guess the question now is adjustable gas block or krink? I've used one before and liked it, but didn't like how it threw off the balance of the rifle. The way I see the KX3 is a device that adds 3" to your barrel to improve functioning, but hell, if I added just another inch to a 5.56 barrel (10.5 vs. 11.5) all the reliability issues are solved right there. so I guess that what I really need to be asking is who makes an adjustable gas block for the 6.8 sbr? or am I just looking to build something that really just can't be built. I see the 10.5 inch ar that can make frag hits out past 150 meters as the perfect battle rifle-period. I live in Georgia, and I don't think that I would ever need to make a shot outside of that range, hell even in Iraq I never shot my rifle at anything past 100 meters and I shot a LOT.

Well have to disagree then. I believe pistons to be more reliable, inparticualr the LW arrangement.

The 6.8 SPC has a short pressure curve and it's not well suited to DI, which is why most DI 6.8s run on mid-length systems, so that they can run a larger port diamter without overgassing. 10.5 DI 6.8s are pretty rare, not to say they don't exist but I have seen the piston rifles chug their way through thousands of rounds of Remington and SSA, with and without cans on barrels form 10.5-16". A lot of it is FA, becuase it's a lot harsher on the guns but also because we have found the 16" 6.8 to be a great for bursts, putting 3-4rounds all on steel at 100m.

It solves the fundamental problem that exists with the 6.8 vis a vis SBRs rather than as a workaround in the form of the KX3 and/or adjustable port. You need to shoot a piston 6.8 and a DI 6.8 with carbine length actions side by side to appreciate what I am talking about.

Supply has been a problem over the last year with the LW guns but we're workign hard to fix that situation presently. Need more info etc? Just give me a holler.

If you want to explore the adjustable gas block idea, contact Marty ter Weeme at Tppo Jutsu, he has some in the works.

OK, i have found an adjustable gas tube from brownell's as well as an adjustable gas block from jp enterprises, I guess that either one will work, but will the jp fit under any FF handguards besides that huge frickin monstrosity by POF? Or am I better off using the adjustable tube and the larue low profile gas block.OOOOOORRRRR am I completely off track again and need to stick with the piston thing? I could care less about carbon coming back into the chamber, I plan on running all chromelined operating gear in the bolt and upper reciever. Again thanks for the help guys, I know I have a lot of questions, I just can't find the answer anywhere else on the site.hinking.gif