CMMG

The 5.7x28mm Barrel and BCG Kit allows you to build an AR in 5.7x28mm using CMMGs 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. CMMGs 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). - TECH SPECS: - CALIBER: 5.7x28mm - BARREL: 8 1:9 Twist Medium Taper 416SS - MUZZLE: threaded 1/2-28 - GAS PORT LOCATION: N/A - FINISH: Salt Bath Nitride - Patented Radial Delayed Blowback - WEIGHT: 1lb 10oz