The Heckler & Koch MR556 A4 pistol is the commercial semi-automatic counterpart to the HK416, combining HK's short-stroke gas piston operating system with a compact 11-inch barrel. The piston system limits hot carbon fouling in the action, helping reduce maintenance and wear during extended use. An adjustable gas regulator supports tuning for suppressed or unsuppressed operation, while the free-float M-LOK handguard provides a slim, adaptable mounting platform. Fully ambidextrous controls and an HK USA enhanced grip improve handling for a wide range of users. Chambered for .223 Remington and 5.56 NATO, the MR556 A4 accepts a 30-round magazine and includes one magazine.

Key features

• Short-stroke gas piston system helps keep hot carbon fouling out of the action
• Adjustable gas regulator supports suppressed and unsuppressed operation
• 11-inch threaded barrel chambered for .223 Remington and 5.56 NATO
• Free-float M-LOK handguard provides flexible accessory mounting
• Fully ambidextrous controls support left- and right-handed operation
• Optic-ready top rail accommodates a wide range of aiming systems

The HK MR556 A4 delivers compact piston-driven performance with ambidextrous controls and adaptable M-LOK compatibility.