I went with piston uppers to help with the gas blow-back. Still get some, but not as bad as with DI. I also used 10.5" barrels. That is about as short as I wanted to go and not be abusive to the can. For mounting, I chose the AAC Blackout Muzzle Brake. It has two baffles to take the brunt of the initial fireball. I have one registered SBR lower and two uppers, one in 5.56 the other in 6.8 SPC. Each upper has its' own AAC M4-2000 Mod-8 Suppressor. The system works and is two tons of fun to shoot.
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