Barrel: 4150V Chrome moly VANADIUM steel, 16" barrel length chambered in 5.56 NATO, with a 1:7 twist, M4 barrel extension, and a mid-length gas system. The A2 profile barrel has a gas nitride finish for accuracy and durabiltly, and is finished off with a .750" diameter low-profile gas block, PSA 13.5" M-Lok Lightweight Free Float Rail, and an A2 flash hider. Upper: Forged 7075-T6 A4 AR upper is hard coat anodized black for durability. Featuring M4 feedramp cuts, these upper upper receivers are made for us right here in the USA **Bolt Carrier and Charging Handle are NOT Included