Barrel: 20" 4150V Chrome Moly vanadium steel, nitride coated and chambered in 5.56 NATO with a 1 in 7" twist. The rifle-length gas barrel is finished off with a quad rail handguard with vertical grip and rail covers, a .750 Front Sight Base, and an A2 flash hider. Upper: Forged 7075-T6 A3 AR upper is machined to MIL-SPECS and hard coat anodized. Uppers include forward assist and dust cover. These uppers are made for us right here in the USA by a mil-spec manufacturer. Includes carry handle assembly. Bolt: Full-auto profile bolt carrier group. Shot-peened, mil-spec Carpenter No. 158A(R) steel bolt. Gas Key Hardened to USGI Specifications, Fastened with Grade 8 screws, and Staked Per Mil-Spec. Lower: This "M16A4" forged lower is quality made using 7075-T6 aluminum and is marked "CAL. 5.56 MM" for caliber. The finish is hard coat anodized. Finished with an A2 Classic Grip, Classic A2 Stock, and rifle-length 7075 buffer tube. The fire control group is a PSA mil-spec finished, single-stage assembly.