The Heckler & Koch MR556 A4 is a compact 5.56x45mm semi-automatic rifle designed for range, duty, and field applications where reliability and reduced maintenance are priorities. Its short-stroke gas piston operating system minimizes carbon fouling and wear on internal components, and the adjustable gas regulator allows tuning for suppressed or unsuppressed use.

This MR556 A4 is built with an 11 inch black threaded barrel and an M-LOK handguard mounted to a Patriot Brown Picatinny rail receiver. Ergonomics include a black synthetic six-position stock, a black polymer grip, and fully ambidextrous controls for ease of handling and manipulation.

Key Specifications

The caliber is 5.56x45mm.
The model is MR556 A4.
The capacity is listed as 10+1.
The barrel length is 11 inches.
The barrel is described as threaded.
The handguard is M-LOK.
The receiver is described as a Patriot Brown Picatinny rail receiver.
The stock is a black synthetic 6-position stock.
The grip is a black polymer grip.
The controls are ambidextrous.

The MR556 A4 employs a short-stroke gas piston operating system that reduces carbon fouling and wear, and its adjustable gas regulator allows the shooter to tune the action for suppressed or unsuppressed operation. Fully ambidextrous controls, reduced weight, and a slim profile make the platform straightforward to operate and maintain.

For those seeking a reliable 5.56x45mm AR-style rifle for the range or duty use, buy the Heckler & Koch / H&K MR556 A4 5.56x45mm online today.