HK MR556A1 223 Remington / 5.56mm NATO 16.5in Black Semi-Automatic Modern Sporting Rifle – 10+1 Rounds

The HK MR556A1 223 Remington / 5.56mm NATO rifle is a civilian-grade AR-style rifle designed for shooters seeking tactical reliability, precision accuracy, and match-grade performance. As a direct descendant of the iconic HK416, this semi-automatic rifle offers the proven durability and advanced engineering that Heckler & Koch is known for. Ideal for home defense, competitive shooting, tactical training, and precision target practice, the MR556A1 delivers exceptional control and versatility.

Cold Hammer-Forged Barrel & Precision Engineering

The MR556A1 features a 16.5-inch cold hammer-forged barrel, crafted from high-grade steel for long-lasting durability and superior accuracy. The barrel includes a 1:7 twist, optimized for 223 Remington and 5.56mm NATO ammunition, ensuring tight groupings and consistent velocity. Its heavy-contour design enhances stability and precision, making it ideal for long-range target shooting and tactical drills.

Reliable Gas Piston Operating System

Using HK’s proprietary short-stroke gas piston system with a solid operating “pusher” rod, the MR556A1 eliminates the malfunctions common to direct impingement AR rifles. Hot gases and carbon fouling are kept out of the receiver, reducing maintenance and enhancing component life. This system provides smooth, reliable operation for extended shooting sessions and competitive events.

Free-Floating Rail System & Optics Ready

The rifle includes a Free-Floating Rail System (FFRS) handguard with four MIL-STD-1913 Picatinny rails for maximum accessory flexibility. A Picatinny rail on the upper receiver allows for optics, scopes, and tactical sights to be mounted easily. Major subassemblies, including the upper receiver/barrel assembly, are fully interchangeable with other high-quality AR-style firearms, making this rifle ideal for custom AR builds, retrofits, and tactical upgrades.

Features and Accessories

• 10+1 round magazine for range and tactical use
• Adjustable diopter front and rear sights
• Full-length MIL-STD 1913 optical rail for red dot sights, scopes, and optics
• Black polymer fixed buttstock for lightweight durability
• Free-Floating Rail System handguard for maximum customization
• Cold hammer-forged 16.5-inch barrel with 1:7 twist optimized for 223 Rem / 5.56mm NATO ammunition
• Short-stroke gas piston system for cleaner, more reliable operation
• Upper receiver/barrel assembly compatible with other AR-style rifles

Specifications

Why Choose the HK MR556A1 223 Remington / 5.56mm NATO Semi-Automatic Rifle?

The HK MR556A1 provides tactical performance and reliability expected from a firearm developed from the world-renowned HK416 platform. With its proprietary gas piston system, cold hammer-forged barrel, free-floating rail system, and optics-ready design, this rifle is perfect for home defense, precision target shooting, competitive matches, and tactical training. Its compatibility with other AR-style assemblies and modular design ensures adaptability for custom builds, upgrades, and retrofits.