The MK18 AR15 style Upper Receiver Group is unmatched in size, weight, and performance, and features the picatinny quad rail Daniel Defense provides to USSOCOM. The RIS II rail features a Bolt-Up System that has been rigorously tested prior to fielding by USSOCOM. The 10.3 inch Cold Hammer Forged barrel is the same length in use for the MK18 upper most commonly used for CQB operations. Its independently ambi GRIP-N-RIP Charging Handle accommodates left- and right-handed shooters. All Daniel Defense complete upper receiver groups come standard with an M16 profile bolt carrier group.