H&K MR556 A4 | 5.56/.223 | 30rd | 81001050

The H&K MR556 A4 is HK-USA’s commercial MR556 A4 AR-style pistol built around a short-stroke gas piston system that reduces direct carbon fouling in the action. It ships with a 30-round magazine, M-LOK handguard, threaded barrel, and fully ambidextrous lower controls. For a reliable, cost-effective optic that pairs well with this platform, consider a Trijicon MRO red dot — compact, robust, and well under $1,000.

Common uses for this configuration include precision practice and range training as well as competition-style target work.

Product Specifications

• The manufacturer is Heckler & Koch / H&K.
• The model is MR556 A4.
• The manufacturer part number is 81001050.
• The caliber is .223 Rem / 5.56 NATO.
• The action is Semi-Auto.
• The standard capacity is 30 rounds.
• The barrel type is Threaded.
• The handguard is M-LOK with ambidextrous QD cups.
• The receiver is a fully ambidextrous lower.
• The NFA thread pattern is 1/2×28.
• The number of magazines included is 1 (30 rd).
• The stock material is synthetic and the stock finish is black.
• The exterior finish is anodized.
• The safety is an ambidextrous safety lever.
• The UPC is 642230269439.

This MR556 A4 presents HK’s commercial take on the MR platform: a piston-driven AR-style pistol intended for operators and enthusiasts who value reduced maintenance and durable components. The combination of a threaded barrel, M-LOK handguard and Picatinny optics rail makes the platform adaptable for a range of sighting and accessory choices. If you want a solid, low-maintenance 5.56/.223 pistol chassis for focused range sessions or competition drills, the MR556 A4 is built to perform.

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