HM Defense Defender M556L 5.56mm NATO / 223 Remington 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 included with each rifle Made in America