HK MR556 A4 5.56 NATO Pistol, 30rd, Black

The MR556 A4 is Heckler & Koch's commercial iteration of the HK416-style platform, updated with a short-stroke gas piston operating system and an adjustable gas regulator to accommodate suppressed or unsuppressed use. It is built with ambidextrous controls and a slim, ergonomic profile intended for reliable operation with reduced maintenance compared to direct-impingement designs. The pistol ships with a single detachable 30‑round magazine and is configured with a threaded barrel and M-LOK handguard.

Key Specifications

• The cartridge is 5.56 NATO (.223 Rem).
• The magazine capacity is 30 rounds.
• The action is Semi-Auto.
• The operating system is a short-stroke gas piston.
• The gas regulator is adjustable for suppressed or unsuppressed use.
• The thread pattern is 1/2x28.
• The barrel twist rate is 1:7 right-hand.
• The unloaded weight is approximately 6.6 lb.
• The handguard uses an M-LOK interface.
• The controls are fully ambidextrous.

Built as a no-nonsense, duty-capable pistol, the MR556 A4 emphasizes reliability, reduced fouling, and modularity. Its piston system and adjustable gas settings make it suitable for a range of shooting applications, from range work to tactical-style configurations, while the threaded barrel and M-LOK handguard support accessory mounting and future upgrades.