CMMG 5.7x28mm 8" BCG and Barrel Conversion with Magazine

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).

Redesigned with a brand-new look, CMMG®’s 5.7 AR Conversion Magazines feature a number of improvements. From the new stylized texture grip and “5.7x28mm” engraving on the sides to the upgraded feed lips, these magazines are built to exceed your expectations. 5.7 AR Conversion Mags are available in 32 or 10 round capacity and are designed to work with CMMG 5.7x28 Radial Delayed Blowback™ Uppers and Mk4/Mil-Spec AR15 lower receivers.