The Radical Firearms 7.5" M4 Profile 5.56mm AR Pistol uses MIL-STD Upper and lower receivers along with our 7" RPR free float rail system for increased accuracy, keeping your hands cool, and giving you plenty of room for accessories. Regardless if it's your first or fiftieth, a Radical Firearms AR pistol will not disappoint! SKU: FP7.5-5.56M4-7RPR UPC: 816903022366 MFR#: RF00133 Barrel Length: 7.5" Barrel Material: 4140 Chrome Moly Vanadium Barrel Finish: Melonite Barrel Profile: M4 Barrel Thread Pitch: 1/2x28 Chamber: 5.56mm Twist Rate: 1:7 Barrel Extension: M4 Feed Ramps Gas System: Pistol Length Gas Block Type: .750 Low Profile Gas Block Muzzle Device: A2 Flash Hider Upper Receiver Material: Forged 7075 T6 Upper Receiver Style: M4 MIL-STD Upper Receiver Finish: Type III Anodizing Forward Assist: MIL-STD Dust Cover: MIL-STD Handguard Type: Free Float Handguard Style: M-Lok Thin Rail Handguard Length: 7" Charging Handle: MIL-STD Lower Receiver: Forged 7075 T6 Lower Receiver Finish: Type III Anodizing Safety: MIL-STD Fire Control Group: MIL-STD Buffer Tube: Pistol Tube Magazine: 5.56 30 Round