CMMG's 8" 9mm 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, Radial Delayed Blowback uses a bolt that is forced to rotate and unlock, slowing the BCG. This results in a lighter BCG for a lighter rifle, and less felt recoil than a straight blowback system.

CMMG's Barrel and Bolt Kits are designed to work exclusively with mil-spec AR-15 upper receivers with a modified ejection port, like CMMG's MkG/MkGs upper, and most mil-spec AR15 lowers when used with 9 AR Conversion mags as well as CMMG's MkGs Mk17 and Mk9* lowers. Other manufacturers’ receivers may work, but we cannot guarantee function or reliability.

*Older Mk9 lowers will require one of CMMG's retrofit kits to convert it to a Radial Delayed Blowback compatible lower, instead of Traditional Blowback.

All CMMG products come with their Lifetime Quality Guarantee.