The Tacfire SS-RK45ACP-LPK rifle build kit contains 45 ACP 16″ barrel/nitride; birdcage flash hider w/crush washer; 15″ slim MLOK free float handguard; AR15 5.56/.223/.300AAC stripped billet upper receiver w/M4 feed ramps, 45 ACP-BCG; AR-15/.556 Mil-Spec charging handle aluminum w/steel latch; dust cover; AR-15 forward assist; AR-15 standard receiver end plate; Mil-Spec/commercial castle nut/steel; buffer tube aluminum;5.5 AR-15 5.5oz 9mm buffer w/tube spring; AR-15 USA made lower parts kit and an AR-15 standard A2 style black pistol grip/A2 style. *Sports South Exclusive.