Heckler & Koch MR556 A4 5.56 NATO

The MR556 A4 from Heckler & Koch is a compact AR-style pistol chambered in 5.56 NATO intended for range, duty, and professional use. It brings HK’s short-stroke gas piston operating concept to a pistol-length platform while retaining ambidextrous controls and accessory compatibility.

The MR556 A4 is built with an HK416-style upper and a slim M-LOK handguard for modular accessory mounting. Controls are fully ambidextrous and the platform ships with a threaded barrel and a collapsible-style pistol tube and ergonomic HK grip for handling and customization.

Key Specifications

• The caliber is .223 REM/5.56 NATO.
• The model is MR556 A4.
• The action is Semi-Auto.
• The magazine capacity is 30 rounds.
• The weight is 6.6 lb.
• The operating system is a short-stroke gas piston.
• The barrel is threaded.
• The stock material is synthetic.
• The receiver is fully ambidextrous.
• The handguard uses M-LOK.

State restrictions: This firearm is not available for sale or direct ship to California, and it is not available for direct ship to Rhode Island or Washington. It is also not for sale in Illinois (PICA).

The Heckler & Koch MR556 A4 delivers proven 5.56 NATO performance with piston-driven operation and modern accessory options. Buy the Heckler & Koch MR556 A4 5.56 NATO pistol online today for a reliable, configurable semi-auto platform.