All Great Lakes AR-15 pistols are chambered in .223 Wylde and feature a 7.5″ barrel in your choice of a beautiful 416r stainless steel or an ultra-smooth 4150 black nitride finish. The .223 Wylde chambers both.223 Remington and 5.56 Nato with equal efficiency and the 1:8″ twist rate is ideal for keeping most bullet weights accurate. The heavy barrel incorporates M4 feed ramps, a .750 gas block, and a pistol-length gas system.