Product Summary
The CMMG AR-15 Barrel and BCG Kit allows you to build a custom AR-15 platform chambered in 5.7x28mm. Featuring a 5-inch medium contour barrel with a 1:9 twist and a nitride finish, this kit is constructed from durable 4140CM steel. It utilizes CMMG’s patented Radial Delayed Blowback operating system, which reduces BCG weight and provides less felt recoil compared to standard direct blowback systems. This kit is designed to fit into a mil-spec AR-15 upper and is compatible with both CMMG Mk57 and standard Mk4/AR-15 lower receivers when used with CMMG 5.7 AR Conversion Magazines.
