Has @MachIVshooter been superceded by his son MachV? This is shocking news!Spend you money with MachV: Cheaper and better product/service. Just in a few weeks E filing of Form 4 is supposed to launch . Will cut the wait quite a bit.
Also guess what : a .30 caliber can on a .5.56 is only a decibel less reduction than a 5.56 one is , al else equal. Id' get a 7" or 8" Mach V one, just a very informed answer with no advertising BS. You can send him the barrel action pr rifle and it will be perfect, you need a 1/2 x28 if its going on ARs .
OP: Gordon is correct that you should at least look at MachIV's offerings. He has some of the best cans on the market that I have seen.