Featuring the same industry leading barrel nut and lock up design as originally introduced on BCM\'s evolutionary KMR handguard, the QRF Series of handguards gives the shooter modularity in the picatinny (MIL-STD-1913) platform. Includes T, L, R, and B recoil slot markings on all four rails to aid in repeatable set up for the end user. This proprietary patented mounting system (US Patent 8904691), includes a mechanical index to the 12:00 rail and positions mounting hardware to mitigate the movement caused by heat generated by the weapon system.