The 5.7x28mm Barrel and BCG Kit allows you to build an AR in 5.7x28mm using CMMG’s patented Radial Delayed Blowback operating system. Unlike typical direct blowback systems, Radial Delayed Blowback not only reduces the weight in your BCG but it results in less felt recoil than a straight blowback system. CMMG’s 5.7x28mm Barrel and Bolt Kits are designed to work with either a CMMG Mk57 lower receiver or with a standard AR15 lower receiver (when using CMMG 5.7 AR Conversion Magazines).

CALIBER: 5.7x28mm

BARREL: 5” 1:9 Twist, Medium Taper 4140CM

MUZZLE: threaded 1/2-28

GAS PORT LOCATION: N/A

FINISH: Salt Bath Nitride

Patented Radial Delayed Blowback

WEIGHT: 1lb 6oz