Heckler & Koch MR556 A4 5.56mm Pistol

The Modern Sporting Rifle Pistol Standard

The Heckler & Koch MR556 A4 represents the pinnacle of short-barreled rifle design, bringing the proven performance of the HK416 platform to a compact, highly maneuverable package. This is a serious tool for serious shooters.

Superior Operating System

The short-stroke gas piston operating system is the foundation of the MR556 A4's reliability. Unlike direct-impingement designs that cycle hot carbon back into the receiver, the piston system keeps your action cleaner, cooler, and running longer between maintenance cycles. This translates to less wear on internal components and more time between cleanings.

The adjustable gas regulator allows you to fine-tune the action for either suppressed or unsuppressed operation, giving you flexibility for different shooting scenarios and ammunition types.

Ergonomic Excellence

Fully ambidextrous controls make this pistol equally at home in either hand. The lighter weight and slimmer profile compared to traditional AR platforms make the MR556 A4 faster to manipulate and easier to employ in dynamic situations.

Specifications

• Caliber: 5.56mm NATO
• Barrel Length: 11 inches with 1:7 twist rate
• Capacity: 10-round magazine (included)
• Handguard: M-LOK compatible for modern accessories
• Sights: Optics-ready upper receiver
• Weight: 6.61 pounds
• Trigger: 4.5 to 5.6 pounds
• Finish: Black throughout

Built for Uncompromising Performance

For shooters who demand an AR-platform pistol with unmatched capability and reliability, the MR556 A4 remains the top-tier solution. This is HK's answer to the question: what does a truly professional short-barreled rifle look like?