HM Defense Defender M556L 5.56mm NATO 16in Black Hardcoat Anodized Semi Automatic Modern Sporting Rifle - 30+1 Rounds. Barrel - the Defender M556L featured HM MONOBLOC barrel with an integrally machined gas block; Chambered in 5.56 NATO/223 Rem, the 4150 chromoly barrel is 16 inches in length, featured a 1:8 twist ratio and a mid-length gas system; All HM Defense barrels are match grade, tripled honed and button rifled for superior accuracy; Rail - the custom HM Defense 15 inches free float 1913 Picatinny rail is CNC machined from 6061 T6 aircraft grade aluminum; The rail is compatible with receiver with type III Class II hardcoat black anodized finish; Lower Receiver - the defender M556L featured a Mil-Spec forged 7075 T6 M4 lower receiver with type III class II hard-coat black anodized finish; Upper receive - Defender M556L featured a Mil-Spec forged 7075-T6 M4 upper receiver with type III class II hard-coat black anodized finish, M4 feed ramps, and a 1913 Picatinny rail flat top; Components - HM defense rifles include an M16 bolt carrier group and Mil-Spec components, including the trigger and fire control group, charging handle and buffer tube/spring; Custom trigger guard, Monobloc dust cover, CNC machined muzzle brake; End plate - HM defense rifles feature a custom quick disconnect (QD) end plate; Furniture - rifle features a black Mil-Spec HM stock and Magpul MOE grip; Magazine - 30 round magazine is include with each rifle; Made in America ;