The latest update from HK-USA to the commercial variant of the legendary HK416, the MR556 A4 and MR762 A4 represent an enhanced example of “no compromise” HK performance. Its short stroke gas piston operating system does not impart hot carbon fouling back into the action, allowing the weapon to run longer, with less maintenance and with less wear on internal components than direct-impingement ARs.   Its adjustable gas regulator allows the operator to tune the action specifically for suppressed or unsuppressed operation.  While fully ambidextrous controls, lighter weight and a slimmer profile make the new A4 easier to operate, manipulate and employ.