The reasons I chose 12.5” are that even though it is halfway between a Mk18 and M4, it handles like a Mk18 to me, but the rail estate and velocity are closer to a 14.5”. Even vs an 11.5”, the velocity gain is just this side of appreciable. I tend to gravitate to longer cans with the shorter barrels, and I also tend to run the stock one click further out on a Mk18 vs M4. So, the 12.5” doesn’t really seem noticeably longer. And unsuppressed, I tend to also use shorter muzzle devices on the 12.5”, which narrows the gap slightly.

It’s just my Goldilocks soup, I guess. Carbine gas is just fine…there are several other features of a barrel that I’d think about before that, which is why all of my 12.5” guns have carbine gas.

Unsuppressed with no intention for a silencer, I’d go longer, though 12.5” is kinda the minimum that I don’t hate unsuppressed.

Thanks, man.

The 10.3 is a good option but the 11.5 is where it’s at.  I have them all and it gets all the love.  


Small sample of some I had out today doing some muzzle devices on.

First one do a 11.5.

But my favorite is a 10.3 or 10.5. suppressed or not.
Handy as fuck rifle. Full 5.56 loads only.
MK18 DD and Colt get shot the most with no suppressor. Not as bad as everyone says. I do like a suppressor on it but not necessarily necessary.

LMT 12" piston.

This.