Heckler & Koch HK MR556 A4 Semi-Auto AR-15 Rifle 5.56 NATO/.223 Rem 16.5in Black M-LOK 30rd

The Heckler & Koch MR556 A4 is a premium, semi-automatic AR-pattern sporting rifle engineered around HK’s proven 5.56mm platform. Chambered in .223 Remington/5.56 NATO and built with a 16.5-inch barrel, it delivers dependable performance for range use, training, and general sporting applications. Finished in a durable black anodized coating, the MR556 A4 pairs rugged construction with refined fit and function typical of HK firearms.

Designed for modern modularity and enhanced handling, the rifle features an M-LOK free-float handguard for accessory mounting while maintaining consistent barrel harmonics. An adjustable gas block allows the system to be tuned for optimal reliability across different ammunition and conditions. Ergonomics are further enhanced with the HK USA Enhanced Grip, a HK416 six-position stock for adaptable length of pull, and ambidextrous controls to accommodate both right- and left-handed shooters.

Features and Benefits:

• Semi-automatic AR platform from Heckler & Koch
• Chambering: .223 Remington / 5.56 NATO
• 16.5" barrel for balanced velocity and handling
• Black anodized finish for durable corrosion and wear resistance
• M-LOK free-float handguard for flexible accessory mounting
• Adjustable gas block for optimized cycling and performance
• HK USA Enhanced Grip for improved control and comfort
• HK416 six-position stock for adjustable fit
• Ambidextrous controls for left- or right-handed operation
• 30-round capacity; includes 1 magazine