HK MR556 A4 5.56 NATO 16.5 in 10+1 CA Compliant

The Heckler & Koch MR556 A4 is a semi-automatic rifle built on HK416-derived components and configured for California-compliant use with a 10+1 capacity. It uses a short-stroke gas piston system and features slimline HK416 furniture, including a collapsible/folding stock. The rifle pairs a 16.5 inch barrel with a threaded muzzle and a fully ambidextrous lower for versatile handling in duty, competition, and precision applications.

Key Specifications

• Chambered in .223 REM/5.56 NATO as listed by the manufacturer.
• Operates as a Semi-Auto action.
• The barrel measures 16.5 inches.
• Standard capacity is 10 + 1 to meet stated compliance configuration.
• Includes 1 10 rd. magazine as specified.
• Equipped with an M-LOK Handguard for accessory mounting.
• Utilizes a Short Stroke Gas Piston system.
• The muzzle is threaded with a 1/2x28 pattern.
• Overall weight is listed as 7.67 lbs..
• Features a Fully Ambidextrous Lower for right- and left-hand operation.

Designed for shooters who prioritize robust engineering and practical modularity, the MR556 A4 integrates proven HK systems with modern accessory compatibility. Its combination of a short-stroke piston, M-LOK handguard, and ambidextrous controls makes it a capable platform for a range of lawful sporting, duty-oriented, and precision roles.