Works well - Midwest Industries Pistol Buffer Tube

I've used this with Colt parts. Colt M4 buffer, M4 buffer spring and bolt carrier group. Never an issue. The additional "shoulder" on the tube puts the Sig arm brace in just the right spot. The whole thing relies on friction to keep the arm brace in place and the two parts were made for each other like the old Reese's peanut butter cup commercials. Hey! You got chocolate on my peanut butter! Yeah, it's that good.