Barrel: Chrome-moly steel, chambered in 5.56 NATO, with a 1:7 twist, M4 barrel extension, and a Mid-length gas system. The A2-style profile barrel is nitride treated for durability and accuracy. Barrel is finished off with an .750 low-profile gas block, 13.5" PSA Lightweight M-Lok Free Float Rail with integrated qd mounts, and an A2 flash hider. Upper: Forged 7075-T6 A3 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. This upper does not include BCG or Charging Handle.