Heckler & Koch MR556A4 Gray 223/5.56 81001308

HK MR556 A4 Features

The MR556 A4’s short-stroke gas piston operating system reduces heat and carbon in the receiver for improved long-term reliability and cooler running under sustained fire. Paired with an HK416 upper and a 16.5" barrel threaded 1/2x28 for muzzle devices, the platform offers excellent durability and straightforward integration of brakes or suppressors while maintaining factory-level accuracy and lockup.

Ergonomics focus on user adaptability and control: a collapsible / folding stock with HK416 slimline furniture, M-LOK handguard for modular accessory mounting, a fully ambidextrous lower and ambidextrous safety lever, and a 30-round magazine configuration to support a wide range of roles. The rifle ships with one 30 rd magazine and a gray Cerakote finish that resists corrosion and reduces glare.

HK MR556 A4 Specifications

• Manufacturer: Heckler & Koch (HK USA)
• Model: MR556 A4
• Family: MR556 Series
• Category: Rifles / AR Style Centerfire Rifles
• Action: Semi-Auto (Short-stroke gas piston)
• Caliber: .223 Rem / 5.56 NATO
• Barrel Length: 16.5 inches
• Barrel Description: Chrome-lined (threaded 1/2x28)
• Rate of Twist: 1-in-7"
• Thread Pattern: 1/2x28
• Finish: Gray Cerakote (applied finish)
• Receiver: HK416 upper; fully ambidextrous lower
• Stock: Collapsible / Folding Stock
• Stock / Furniture: HK416 Slimline Furniture
• Handguard: M-LOK handguard
• Capacity: 30 + 1
• Included Magazines: 1 × 30 rd
• Sights: None (optic cut / optic-ready not specified)
• Weight: 7.67 lbs
• Overall Length: 33.25" to 36.5" (stock collapsed/extended)
• Number of Magazines: 1
• Special Features: Threaded barrel; short-stroke gas piston; HK416 upper receiver; M-LOK handguard; fully ambidextrous controls; ambidextrous safety lever
• Shipping Weight: 14.4 lbs.
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