16″ 5.56 NATO 1:7 Twist Black Nitride Mid-Length Barrel If you are looking for your next AR 15 barrel, this 16″ 5.56 NATO has a mid-length gas system, is manufactured here in the United States from 41V50 barrel steel, and comes Black Nitride treated for added corrosion resistance, which adds to barrel life. This 16″ AR-15 barrel is backed by a limited lifetime warranty and a 1″ MOA Guarantee when used with factory match-grade ammunition. Features Length: 16″ Cartridge Compatibility: 5.56 NATO Gas System Length: Mid-length Gas Block Journal: .750″ .076″ Gas Port Size Twist Rate: 1:7