CMMG MR Barrel Black 5.56 / .223 Rem 12.5-inch

Perfect for building your custom AR-15 upper group. Comes with properly installed M4 barrel extension. All barrel sub-assemblies are properly headspaced. Features and Specifications: Manufacturer Number: 55DDF0A 12.5 Multi Role Profile 4140 Chrome Moly Salt Bath Nitride Finish inside and out 1:7 Twist 5.5645 NATO Chamber Threaded 1/2-28 Carbine length gas port .750 Gas Journal