HK MR762 A4 13" 5/8x24 Threaded Barrel Upper Receiver Kit 51001919

The MR762 A4 Upper Receiver Kit is a factory-built upper/barrel assembly from Heckler & Koch designed to convert a Mil‑Spec 7.62×51mm AR‑style lower (or pair with an MR762 lower) to HK’s short‑stroke piston system. It gives the MR762/compatible platform the same rugged, field‑proven piston/pusher‑rod operating system used on the HK417 family—keeping hot gases and carbon out of the receiver for improved reliability and reduced maintenance.