Heckler & Koch Rifle Uppers for Sale

Heckler & Koch GmbH of Germany entered the rifle uppers space in the early 2010s with AR-compatible upper receiver kits, bringing the MR556A1 Upper Receiver Kit to the U.S. by 2012 and offering HK416 upper kits to law enforcement and military users. These factory piston-driven assemblies retrofit non-HK AR-15/M4 lowers with the 416/MR556 short-stroke pusher-rod system and are sold as complete kits with a proprietary buffer and action spring, pairing German cold-hammer-forged barrels and a C.I.P.-dimensioned chamber with commercial semi-auto timing (the MR556A1 uses a 16.5-inch, 1:7-twist unlined, slightly swagged bore), while HK416 kits are configured to mate with select-fire lowers.