The HK MR556 A4 rifle in 5.56x45mm with an 11-inch threaded barrel (brand part no. 81001202) uses a short-stroke gas piston operating system that keeps hot carbon fouling out of the action, letting the rifle run longer with less maintenance and less wear on internal components. Heckler & Koch equips the A4 with an adjustable gas regulator to tune the action for suppressed or unsuppressed operation, and fully ambidextrous controls, a lighter weight, and a slimmer profile make the A4 easier to operate and manipulate. The rifle carries a 10+1 capacity with an M-LOK handguard, a Picatinny rail receiver, and a 6-position stock. Among gas-piston semi-auto firearms, this MR556 A4 configuration favors shooters who want low-maintenance reliability with suppressor-tunable gas settings.

Key Specifications

• Chambered in 5.56x45mm/.223 Remington.
• Capacity of 10+1 rounds.
• The barrel measures 11 inches and is threaded.
• The operating system is a short-stroke gas piston, keeping fouling out of the action.
• The gas regulator is adjustable for suppressed or unsuppressed operation.
• The controls are fully ambidextrous.
• The handguard uses M-LOK attachment slots on a Picatinny rail receiver.
• The action is semi-automatic, cycling a fresh round into the chamber with every trigger pull.
• Equipped with a Ambidextrous Safety Lever safety.

Frequently Asked Questions

Can the gas system be tuned for a suppressor? Yes, the adjustable gas regulator lets the operator tune the action for suppressed or unsuppressed use.

Are the controls ambidextrous? Yes, the A4 uses fully ambidextrous controls throughout.

Buy the HK MR556 A4, 11-Inch Barrel

Low-maintenance, suppressor-tunable reliability is exactly what this MR556 A4 delivers. Order it from our Lubbock, Texas gun shop for fast, insured shipping to your FFL.