Barrel: 416R stainless steel barrel. Chambered in 6.8 SPC II, with a 1:11 twist rate, M4 barrel extension, and a mid-length gas system. Barrel is finished off with a PSA 15" Hex Full Picatinny M-Lok Free Float Rail, .750" adjustable low-profile gas block, and an A2-style flash hider. Upper: Forged 7075-T6 aluminum A3 AR upper is made to MIL-SPECS and hard coat anodized black for durability. These uppers are made for us right here in the USA by a mil-spec manufacturer. Bolt: 9310 steel bolt assembly which is nitride treated for durability. BCG has an 8620 carrier, nitride treated, with a nitride treated gas key properly staked with grade 8 fasteners.