The Heckler & Koch MR556 A4 is a compact semi-automatic platform built around H&K’s short-stroke gas piston system and an 11-inch threaded barrel. This variant features an M-LOK handguard, a Picatinny rail receiver, and fully ambidextrous controls intended for duty, range use, and compact carry applications where a shorter-barrel AR-pattern pistol is appropriate. The design emphasizes reduced fouling and adjustable gas control for suppressed or unsuppressed operation.
Key Specifications
- The model is MR556 A4.
- The caliber is .223 Rem / 5.56 NATO.
- The barrel length is 11 inches.
- The barrel type is threaded.
- The action is Semi-Auto.
- The handguard features M-LOK attachment points.
- The finish is Black (Anodized).
- The rate of twist is 1-in-7″.
- The NFA thread pattern is 1/2×28.
- The receiver is a fully ambidextrous lower.
The MR556 A4 delivers the proven short-stroke gas piston operation and modular ergonomics that experienced shooters expect from H&K. Its compact 11″ configuration, threaded barrel and M-LOK handguard make it a versatile platform for range work and purposeful compact applications where a reliable, low-maintenance system is preferred.
Product information is supplied by the manufacturer and/or distributor and may be automatically formatted or enhanced using AI for clarity and consistency. While we strive for accuracy, specifications, features, and included items may change without notice. Always verify details using the manufacturer’s official documentation and the information shown on this product page before purchase or use.
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