This Heckler and Koch MR556A4 upper receiver kit brings genuine HK engineering to your existing lower, built around an 11-inch barrel chambered in 5.56mm. The MR556 platform is the civilian descendant of HK's renowned HK416 — the short-stroke gas piston system that earned its reputation in the world's most demanding service environments by running cleaner and cooler than direct impingement designs. HK's cold-hammer-forged barrels are considered among the finest in the world for accuracy and service life. Note the 11-inch barrel length: assembling this on a lower requires proper NFA or pistol configuration compliance.

In stock and ready to ship straight to your door from Dawson Defense, an Arizona-owned licensed dealer.