These barrels are cold hammer-forged from high-grade chromium-molybdenum-vanadium alloy steel for exceptional strength and accuracy potential—like a high-end match rifle barrel. Magnetic particle inspection (MPI) ensures there are no internal flaws in the metal. Durable manganese phosphate finish give excellent resistance to surface wear. Barrel extension has M4-type feed ramps. Choose caliber, profile and length. 5.56x45 barrels come in 10.5”, 14.5” and 16” lengths, with the shorter barrels featuring carbine length gas system. Barrels are available in lightweight or government contours, and M4 for the 14.5” length. OD at gas block is .750”.