Like the HK416, the MR556A1 uses a proprietary HK short-stroke gas piston in place of the direct-gas-impingement system found on lesser AR15-style rifles that propels exhaust gas into the upper receiver to operate the action.
The MR556A1’s barrel is cold hammer forged from the highest quality cannon-grade steel. It has a 1 in 7” twist and a taper-bore configuration, with a slightly smaller diameter at the muzzle for improved accuracy and velocity. And while the material and cold hammer forging process themselves greatly enhance durability, HK’s processes include many additional steps not taken by other manufacturers to produce superior accuracy and service life, ensuring performance well beyond “mil-spec.”
|Black Synthetic/ Adjustable
|16.5 Medium Contour Barrel
Determined at checkout.