Abstract: A firearm including a barrel having a breech and a muzzle defining a length of the barrel is disclosed. The firearm includes a hand guard having a first end and a second end with a front sight is attached to at least one of the barrel adjacent the muzzle and the second end of the hand guard. A housing is coupled to the front sight and defines a chamber having a piston disposed therein and movable between static and displaced positions. A receiver is coupled to the first end and a bolt carrier is disposed within the receiver and moveable between firing and rearward positions. A carrier key is attached to the bolt carrier and moves concurrently with the bolt carrier and a rod is permanently affixed to the carrier key and extends to a distal end with the piston engaging the distal end when moving to the displaced position.

Abstract: A firearm includes a receiver and a barrel connected to the receiver. A hand guard extends from the receiver and defines a hand guard bore. The receiver includes a threaded end and the hand guard includes a flange extending into the hand guard bore and abutting the receiver about the threaded end. A hand guard nut abuts the flange of the hand guard and threadedly engaging the threaded end of the receiver. The hand guard nut sandwiches the flange between the hand guard nut and the receiver for attaching the hand guard to the receiver. The hand guard includes a first hand guard portion and a second hand guard portion removably attached to the first hand guard portion. The second hand guard portion is slid from an assembled position to a disassembled position to expose the hand guard nut in the hand guard bore.