Bilson Arms BA-15FC 5.56 NATO 16in Forward Complete Upper Assembly Standard Carbine Length 1-7 Twist 1/2x28 A2 Flash Hider Nitride Fde/Sniper Green. 56 NATO 16 inch 4150/4151 CrMoV barrel with FDE & Graphite Black Cerakote Specifications for Bilson Arms BA-15FC 5.56 NATO 16in Forward Complete Upper Assembly: Manufacturer: Bilson Arms Caliber: 5.56x45mm NATO Barrel Length: 16 in Gas System Length: Carbine Length Barrel Twist Rate: 1-7 Threads per Inch: 1/2x28 Finish: Cerakote Fabric/Material: 6061-T6 Aluminum Features of Bilson Arms BA-15FC 5.56 NATO 16in Forward Complete Upper Assembly Bilson Arms patented forward charging design Package Contents: Bilson Arms BA-15FC 5.56 NATO 16in Forward Complete Upper Assembly Comes in a plastic hard case with a gun lock and owners manual Bilson Arms ARUFCFG10R1: BA-15FC 5.56 NATO 16in Forward Complete Upper Assembly Standard Carbine Length 1-7 Twist 1/2x28 A2 Flash Hider Nitride Fde/Sniper Green