16 rifle kit comes with everything needed to complete a stripped lower receiver. Includes fully assembled headspaced and test fired upper receiver lower parts kit and buttstock. - Barrel: - Chrome Moly Vanadium - M4 Feed Ramps - 16 Length - 1x9 Twist - A2 Flash Hider - Manganese Phosphated - Phosphated under Front Sight Base - Taper Pins in F-marked Front Sight Base - Threaded Muzzle - Heavy Profile - Chamber: - 5.56 X 45 mm - Bolt And Carrier: - Phosphated 8620 Steel Carrier Assembly - Carpenter 158 Bolt HPT/MPI Tested - Heat Treated and Plated - Mil-Spec - Chrome Lined Carrier Interior - Carrier Key - Chrome Lined attached with Grade 8 Screws - Properly Staked & Sealed Gas Key - Handguards: - Carbine Length - Aluminum Delta Ring - Single Heat Shield - Upper Receiver: - Forged 7075 T6 Aluminum - A3 Flat Top with M4 Feed Ramps - Hard Coat Anodized - Mil-Spec - Ejection Port Cover and Round Forward Assist - Right Hand Ejection - Bore's surface is coated with dry film lube over the anodized surface - Buttstock: - M4 5 Position - Reinforced Fiber - Mil-Spec Sized Tube