Barrel: Nitride finished 4150V chrome moly vanadium 16" barrel. Chambered in 5.56 NATO, with a 1:7 twist rate, M4 barrel extension, and a carbine length gas system. Barrel is is finished off with Magpul MOE Flat Dark Earth carbine length handguards, F-Marked gas sight base, and an A2 flash hider. Upper: Forged 7075-T6 A3 AR upper is made to MIL-SPECS and hard coat anodized for durability. These uppers are made for us right here in the USA by a mil-spec manufacturer. Bolt: Full-auto profile bolt carrier group. Milspec Carpenter No. 158A(R) steel bolt, shot peened, gas key hardened to USGI Specifications, fastened with grade 8 screws, and staked per Mil-Spec. 8620 steel M-16 profile carrier is chrome lined and phosphate coated. Includes: Magpul MBUS Rear Backup Sight, Black#html-body [data-pb-style="62DF8287BCD2A"]{justify-content: flex-start; display: flex; flex-direction: column; background-position: left top; background-size: cover; background-repeat: no-repeat; background-attachment: scroll; border-style: none; border-width: 1px; border-radius: 0px; margin: 0px 0px 10px; padding: 10px;}#html-body [data-pb-style="62DF8287BCD37"]{border-style: none; border-width: 1px; border-radius: 0px; margin: 0px; padding: 0px;}