Well, I took advantage of the fire sale on the EE of the 7.5" 6.8 SPC pistol barrels.  I have the barrel in hand and all the necessary parts for the build except for the pistol length gas tube and plan on starting the build soon.  I still need a FH and was hopping to use my 30 cal BABC but realized these barrels are threaded 1/2 x 28 which is the thread usually found on the 5.56 rifles.  The thread pitch WAS mentioned in the EE ad, but I didn't think it would be a problem.  Now I see it is. I have started looking around for a 30 cal FH with 1/2 x 28 threads similar to the KKX PIG.  Fortunately, I have an extra 30 cal GEMTECH FH purchased a few months back for use with my Quicksand on one of my AR-15s.  I can use that FH for this build but I think it will still be noisy and produce a big flash. I would really prefer something like the PIG or the BABC.  Does anyone know of a 30 cal FH besides the Gemtech that is more like the PIG or BABC with the 1/2 x 28 threads?

I have one of these barrels coming also.   The two options I have found is get a thread adapter from Brownell that takes you from the 1/2 to 5/8.   Or get the following with was made for the 7.62 but has the adapter already installed.  http://www.maddogweapons.com/store/p134/Black_River_Tactical_Covert_Comp_-_"5.56"%2C_1%2F2-28_Thread%2C_Fluted.html

Thanks. I thought about the thread adapter also but wasn't sure how well it would work on the 6.8. Since I already have the 30 cal BABC, it would be the less expensive option. I'll look at the other option you mentioned also.  ADDED:  I went ahead and ordered the shoulder less thread adapter from Brownells since it will give me more flexibility should I decide to get a different FH/compensator.

What flash hider do you want to use?



You can probably bore out a 5.56 suppressor to pass the 6.8.  Some probably won't even need bored out.  Brakes are more likely to have a tight fit.

       
 

I already have a 30 cal suppressor I could use--the Gemtech Quicksand--but I understand they shouldn't be used with a barrel this short, plus it would double the length of the barrel. I was looking for something to direct sound from the shooter, something like the Pig which seems to be getting good reviews.

This should work for you:



http://www.kineti-tech.com/create-a-2-piece-muzzle-brake-cucussion-sound-redirector/



They use a 5/16 through hole, so .312, it shouldn't have any problems with .277 projectiles.  Works as a muzzle brake, then has attachable can for redirecting flash and concussion.  Available with 1/2x28 threads.

       
 

The Noveske Kx3 in 1/2x28 will work fine. I have one on a 9mm SBR. An entire 9mm cartridge will drop clean through the thing.

This was going to be my suggestion as well.

I have the 30 cal 5/8 -24 on my 6.8 and like the way it functions and diverts the blast forward with little change to the recoil when the shroud is on. A lot of people complain the bore size is too large for the 223. Should be just right for the 6.8.

Thanks for the link! I picked up one of these barrels as well, going to give this brake a shot. Could always ream it out if its too tight

Hey, I fell for that deal in the EE too.

My research turned up several 1/2 28 flash hiders for 6.8 from midwayusa.  Although, I'm thinking of milling out a 556 A2 flash hider to keep this build on the cheap.