BCM GUNFIGHTER MCMR Aluminium Rail - 5.56, mlok slot - Platform - AR15- HandgunFeaturing the same industry leading barrel nut and lock up design as originally introduced on BCM's evolutionary KMR handguard, the MCMR Series of handguards gives the shooter modularity in the M LOK platform. 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.