Heckler & Koch MR556 A4 5.56 11″ 10+1 Gray

The Heckler & Koch MR556 A4 is a semi-auto 5.56 REM/5.56 NATO firearm configured with an 11" barrel and a 10+1 magazine capacity. It includes a gray Cerakote finish, an HK416 upper receiver and an M-LOK handguard for modular accessory mounting. The lower is fully ambidextrous and the action is listed as semi-auto with a short-stroke gas piston system.

Key Specifications

• Caliber is .223 REM/5.56 NATO.
• The barrel length is 11".
• Standard capacity is 10 + 1.
• The finish is Gray Cerakote.
• The action is listed as Semi-Auto.
• The listed weight is 6.61 lbs..
• The rate of twist is 1-in-7".
• The lower is described as Fully Ambidextrous Lower.
• The NFA thread pattern is 1/2x28.
• Notable features include a Short Stroke Gas Piston, HK416 Upper Receiver, and M-LOK Handguard.

Designed to serve in modern utility and range roles, the MR556 A4 pairs compact barrel length with a feature set aimed at modularity and ambidextrous handling. The combination of an HK416 upper, M-LOK interface, and a short-stroke piston system provides a platform suitable for precision-oriented range use and practical field applications. Its gray Cerakote finish and accessory-ready handguard make it adaptable to a range of setups for users who value durability and straightforward functionality.