CMMG 57D0476 Barrel and Bolt Carrier Kit 5.7x28mm 16.1"

For the discerning firearms enthusiast looking to build a versatile AR platform, the CMMG 16.1" 5.7x28mm Barrel and BCG Kit offers an exceptional solution. This kit is engineered for those who wish to construct either an AR pistol or a short-barreled rifle (SBR) chambered in the dynamic 5.7x28mm cartridge.

The heart of this system is CMMG's patented Radial Delayed Blowback operating mechanism, which stands apart from conventional direct blowback systems. By reducing bolt carrier group (BCG) weight and diminishing felt recoil, it provides improved handling without compromising on essential features like last round bolt hold open—a crucial aspect for tactical readiness.

This barrel and bolt assembly seamlessly integrates into a Mk4/mil-spec AR15 upper receiver and can be paired with either a CMMG Mk57 lower receiver or any Mk4/AR15 mil-spec lower when using CMMG’s proprietary 5.7 AR Conversion Magazines.

Whether your goal is precision shooting or reliable performance under demanding conditions, this kit ensures you have both adaptability and superior control over your firearm configuration.