Barrel and BCG Kit, 8" 4140CM, SBN, 40 S&W

The CMMG® 8” 40 S&W MkGs Barrel and BCG Kit allow you to build a Pistol Caliber Carbine using our Patent Pending Radial Delayed Blowback System. Unlike typical direct blowback systems, our RDB uses a bolt that is forced to rotate and unlock, slowing the BCG. This results in a lighter BCG for a lighter pistol or rifle, and less felt recoil than a straight blowback system.

Our MkGs Barrel and Bolt Kits are designed to work exclusively with our MkGs Lowers. Other manufacturers’ receivers may work, but we cannot guarantee function or reliability. 

All CMMG products come with our Lifetime Quality Guarantee.

Platform MkGs

Caliber .40 S&W

Operating System Radial Delayed Blowback

Barrel Length 8

Barrel Twist 1:16

Barrel Contour MT

Barrel Material 4140CM

Muzzle Thread 0.578 x 28

Gas Port Location N/A

Gas Block N/A

Finish SBN

Weight 1.7 lbs