HK MR556 A4 Upper Receiver Kit for AR15/M16/M4, 11" Barrel, 5.56mm, Black

Overview:

The HK MR556 upper receiver kit offers a factory-quality upper assembly designed to fit AR-15/M16/M4 platforms. Built to HK’s rigorous standards, this 11" kit pairs a precision 5.56mm barrel with a full-length Picatinny receiver interface for reliable accuracy, robust accessory mounting, and service-grade durability in a compact package.

Key Features:

• Brand: HK (Heckler & Koch)
• Series / Model: MR556 — Upper Receiver Kit
• Category: Uppers
• Caliber: 5.56mm
• Firearm Fit: AR15 / M16 / M4
• Color / Finish: Black
• Barrel Length: 11"

Applications:

• Ideal For: Compact carbine builds, patrol / duty uppers, and short-barrel rifle (SBR) style configurations (where legal).
• Use Case: Builders and armorers seeking a factory-style upper with HK fitment and accessory-ready Picatinny interface.

Additional Features:

• Accessory Ready: Full-length Picatinny receiver interface for optics, sights, and mounts.
• Handguard / Mounting: Designed to accommodate standard accessory mounting and rail systems.
• Durability: Finished in black to match common AR components and provide corrosion resistance.

MPN: 51000385

UPC: 642230270220

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