Like its 5.56 mm counterpart the MR762A1 is a direct semi-automatic descendent of the HK416/417 series. It is assembled in the USA using US and German-made components and uses many of the same parts and assemblies developed for the legendary HK416 and 417. - This latest update to the MR762A1 includes an updated grip and forearm as well as a lighter barrel profile that removes nearly a pound of front-end weight from the rifle. - Like the HK416/417 the MR762A1 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. In the �closed� HK piston system exhaust gasses never enter the receiver which means the HK runs cooler cleaner. That is where that legendary HK reliability comes from. - When adverse conditions like dust sand and mud are introduced the advantage of the HK system becomes even more drastic. That is why so many of the world�s military and law-enforcement elite customers trust HK. - The MR556A1�s barrel is cold hammer forged from the highest quality cannon-grade steel with a slightly smaller diameter at the muzzle for improved accuracy and velocity. 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.� - Caliber 7.62 x 51 mm NATO - Operating principle Gas operated short stroke piston - Bolt system Rotating bolt - Magazine 10/20 rounds - Mode of fire Semi-automatic - Length maximum (stock extended) 39.50 in / 1003 mm - Length minimum (stock retracted) 36.00 in / 914 mm - Width 3.23 in / 82 mm - Height 8.39 in / 213 mm - Barrel length 16.5 in /421 mm - Weight Rifle (with empty magazine) 8.84 lb /4 kg - Trigger pull 4.5�5.6 lb / 20�25N ( two stage trigger) - Barrel profile 4 lands & grooves right twist 1 in 11.02 in (280 mm) - Sights Optics ready - Adjustable buttstock 6 positions 80 mm of travel