CMMG Barrel and BCG Kit, 8" 4140CM, SBN, 9mm, 99D517A

Our 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.

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

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

All CMMG products come with our Lifetime Quality Guarantee.