TacFire RK556LPK: TacFire\'s AR-5.56 Unassembled rifle build kit includes a black parkerized barrel with a 1:8 twist rate, 1/2x28 A2 flash hider; a Slim M-Lok free-float handguard; 7075-T6 billet aluminum stripped upper; 5.56 bolt carrier group; Mil-Spec charging handle, dust cover, forward assist, carbine length gas tube, low profile gas block; complete mi-spec M4 stock and lower parts kits all made in the USA. This model has a 16\" barrel and 15\" handguard.