Perfect for building your custom AR15 upper group. Comes with a properly installed M4 barrel extension. All barrel sub-assemblies are properly headspaced. Chambered in .300 Blackout 16.1" Barrel Length Medium Taper Contour Carbine Gas System Length 5/8-24 Threads 1-7 Barrel Twist Available in a Bead Blasted Stainless Steel or Salt Bath Nitride Finish Mfg: Cmmg
