This M4 upper receiver is ready for the range! It features a 14 1/2″ barrel with a permanently affixed A2 extended flash hider. Its 16 3/8″ overall length makes it legal for use on standard semi-auto rifles. The highly accurate barrel is machined from 4150 Chrome Moly Vanadium 11595E Steel and is chrome-lined in both bore and chamber for long wear and ease of cleaning. The 1-in-7 rifling will stabilize bullets from 50 to 80 grains. A standard A2 front sight is fitted. The flat top upper receiver is complete with bolt carrier assembly, charging handle, forward assist, ejection port cover, and removable A4 carry handle with a 300 – 600 meter dual aperture rear sight. A black manganese phosphate finish protects it against rust and corrosion. Option to purchase as a complete upper receiver or without bolt and charging handle.