The MR556A1 is the civilian semi-automatic version of the HK416 for the US market, featuring the same short-stroke gas piston system and 16.5-inch barrel with M4-compatible lower receiver. It brings the HK416's operating system to civilians while complying with US regulations. Uses standard STANAG magazines. Type: Semi-Auto Rifle Action: Short-Stroke Gas Piston Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2010, Germany Weight: 8.6 oz Overall length: 35.43" Status: Active Intended use: Sport Shooting, Home Defense, Collector