EDEMO Rosco OPMOD Bloodline 5.56mm Nato 13.9in Threaded Barrel Government 1-7 Twist Rate 1/2x28 TPI Black Nitride BL-1395-GVT-556-7-M EDEMO4. 9in M4 5.56 NATO Mid-Length barrel was designed around the USASOC specs for an Improved Upper Receiver Group...