Barrel: Chambered in 300AAC Blackout with a 1:7 twist rate, M4 barrel extension, and a pistol gas system this barrel is nitride treated for accuracy and durability. It is finished off with a PSA 7" Lightweight M-Lok rail, .750" diameter low profile gas block, and an A2 flash hider. Upper: Forged 7075-T6 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. ** Upper Does Not Include BCG or Charging Handle.