The HK MR556 A4, a direct commercial variant of the proven HK416 platform, represents a significant enhancement in AR pistol performance. Its short-stroke gas piston operating system effectively mitigates hot carbon fouling from the action, optimizing operational longevity, reducing maintenance cycles, and minimizing wear on critical internal components compared to direct-impingement systems. The integrated adjustable gas regulator allows operators to fine-tune performance for both suppressed and unsuppressed configurations. Featuring fully ambidextrous controls, a reduced weight profile, and a slimmer chassis, the MR556 A4 facilitates enhanced manipulation and rapid deployment. For users requiring an AR platform with uncompromising reliability, durability, and a demonstrable capability envelope, the MR A4 series remains a benchmark solution.
Key Features
Short-Stroke Gas Piston System
The core of the MR556 A4’s operational superiority is its short-stroke gas piston system. This design prevents hot, corrosive carbon fouling from entering the receiver, which is a common limitation in direct-impingement systems. The result is significantly reduced internal component wear, enhanced reliability in adverse conditions, and extended intervals between required maintenance.
Adjustable Gas Regulation
An operator-adjustable gas regulator is integrated, allowing precise tuning of the weapon’s action. This feature is critical for optimizing performance when alternating between suppressed and unsuppressed firing, ensuring consistent cycling and mitigating excessive gas blowback to the shooter.
Ergonomic and Ambidextrous Controls
The A4 variant incorporates fully ambidextrous controls, providing seamless operation for both left and right-handed users. This design minimizes transition time and enhances weapon manipulation under dynamic conditions. The re-engineered chassis contributes to a lighter overall weight and a slimmer profile, improving handling characteristics and reducing shooter fatigue during prolonged use.
Robust Construction and Proven Reliability
Constructed to HK’s stringent manufacturing standards, the MR556 A4 utilizes high-grade materials and precision machining. This commitment to robust construction ensures exceptional durability and long-term operational reliability, even under high-volume use or in demanding environments. As a direct descendant of the HK416, it inherits a lineage of military-proven performance.
Technical Specifications
Model
HK MR556 A4
Caliber
5.56x45mm NATO (.223 Remington compatible)
Operating System
Short-Stroke Gas Piston
Barrel Length
11 inches
Capacity
30 Rounds
Finish
Black
Controls
Fully Ambidextrous
Gas System
Adjustable Regulator
Platform Type
AR Pistol
SKU
LIP|HK81001050
