Item #:
642230271050
UPC: #:
642230271050
availability:
in stock

HK MR556 A4 5.56x45mm 11" Barrel 30+1 Patriot Brown Receiver

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The HK MR556 A4 delivers HK416-derived engineering in a civilian-legal configuration, combining German precision manufacturing with modern tactical features. This 5.56x45mm rifle features an 11-inch threaded barrel and distinctive Patriot Brown Picatinny rail receiver that sets it apart from standard black configurations.

What Makes This Different

Built on HK's proven gas piston operating system rather than direct impingement, the MR556 A4 runs cleaner and cooler under sustained fire. The proprietary HK gas system reduces fouling in the action by 75% compared to AR-15 platforms while maintaining the familiar ergonomics and manual of arms. Cold hammer-forged barrel construction delivers consistent accuracy across temperature extremes and extended firing schedules.

Key Features

  • HK proprietary short-stroke gas piston system for enhanced reliability
  • 11-inch cold hammer-forged barrel with 1:7 twist rate and threaded muzzle
  • Patriot Brown anodized Picatinny rail receiver with full-length top rail
  • Free-floating M-LOK handguard for accessory mounting flexibility
  • Ambidextrous safety selector and magazine release controls
  • 6-position collapsible stock with multiple length-of-pull adjustments
  • 30-round polymer magazine included with purchase
The MR556 A4 excels in close-quarters applications where maneuverability matters most. Law enforcement agencies appreciate the compact profile for vehicle operations, while competitive shooters benefit from the inherent accuracy of the cold-forged barrel. The threaded muzzle accepts standard 1/2x28 muzzle devices including compensators, flash hiders, and suppressors when paired with appropriate tax stamps.

Technical Specs

  • Caliber: 5.56x45mm NATO/.223 Remington
  • Barrel Length: 11 inches, cold hammer-forged with 1:7 twist
  • Overall Length: 28.5-31.5 inches (stock collapsed/extended)
  • Weight: 8.6 pounds unloaded
  • Magazine Capacity: 30+1 rounds
  • Operating System: HK proprietary short-stroke gas piston
  • Receiver Finish: Patriot Brown anodized aluminum
  • Handguard: Free-floating M-LOK compatible
  • Stock: 6-position collapsible synthetic
  • Safety: Ambidextrous selector
  • Country of Origin: Germany/USA
The MR556 A4 represents HK's commitment to bringing military-grade reliability to civilian applications without compromise. Limited production runs of the Patriot Brown receiver finish make this configuration particularly sought after among collectors and serious users alike.