US Patent 8726557 Hand guard attachment system for firearms

A hand guard attachment assembly for a firearm having a barrel and a receiver fastened to the barrel by a barrel nut. The hand guard attachment assembly includes a forearm having a monolithic mounting rail/hand guard that is removably connected to the receiver. The monolithic rail/hand guard interfaces with an integral multi-slot mounting portion of the receiver. A cinch block is mated to the slots of the receiver and held in place by the monolithic rail/hand guard. A tension block is mated at one end of the monolithic rail/hand guard and is attached to the cinch block by a fastener to securely hold the monolithic rail/hand guard in place.