Heckler & Koch MR556 A4 — 5.56 NATO, 11″ Barrel, 30+1

The MR556 A4 uses a short-stroke gas piston operating system designed to limit hot carbon fouling in the action, reducing routine maintenance and internal wear. An adjustable gas regulator allows tuning for suppressed or unsuppressed operation. Fully ambidextrous controls, reduced weight and a slimmer profile improve handling and manipulation in a variety of field roles.

Key Specifications

• The caliber is .223 REM/5.56 NATO.
• The barrel measures 11".
• The maximum listed capacity is 30 + 1 rounds.
• The action type is Semi-Auto.
• The overall length is 26.50".
• The unloaded weight is 6.61 lbs.
• The grip material is Black Polymer.
• The stock material is Synthetic with a Black finish.
• The controls include a Ambidextrous Safety Lever.
• Features a short-stroke gas piston with an adjustable gas regulator and an M-LOK handguard.

Designed for users who expect durable function and straightforward ergonomics, the MR556 A4 pairs the cleanliness advantages of a piston system with ambidextrous controls and contemporary accessory compatibility. Its compact 11" barrel and modular rail make it suitable for applications that benefit from a shorter platform while retaining the utility of standard 5.56 NATO ammunition and a high-capacity magazine option.