The FightLite Industries MCR556DFRM belt-fed upper receiver assembly is designed to interchange with standard AR/M4 type uppers and readily fits any MIL-Spec lower receiver without permanent modification to the host lower, and is rearward compatible to AR15/M16 models produced as early as 1963. The MIL-Spec MCR 5.56 DFR takes the standard MCR technology to a whole new level and includes all of the accessory items that are included in the standard MCR government product along with Dry Film Lubrication on critical high-friction surfaces for extra performance in extreme conditions.Once installed, the patented MCR upper receiver system can be user-configured in seconds without tools to adapt to virtually any mission profile. Specifically designed for responsible armed citizens, law enforcement and professional security personnel who wish to upgrade their rifle or carbine to MCR performance and capability; standard features include gas-piston operation for extreme reliability in adverse ...