• HK416 elongated steel castle nut
• HK416 A5 upper receiver
• Continuous picatinny rail interface between upper receiver and handguard
• M-LOK interface with integral ambi QD cups
• Suppressor-ready concentric 5/8X24 threads
• Match rifle cold-hammer-forged barrel
• Ambidextrous safety lever, bolt release and magazine release
• Ambi safety selector with 45-degree throw
• Updated angled magazine well for reliable feeding
• HK416 2-position adjustable gas block
• Ambidextrous QD end plate

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. Fully ambidextrous controls, lighter weight and a slimmer profile make the A4 easier to operate, manipulate and employ. For those who demand an AR with unmatched capability and uncompromising reliability and durability, the MR A4s remain the top tier solution.