H&K MR556 A4 Upper Receiver Kit – 11″

MR556 A4 Upper Receiver Kit Description

Upgrade your Mil-Spec 5.56mm AR-style rifle with this complete MR556 A4 Upper Receiver Kit, designed to integrate HK’s advanced piston and pusher rod system. Replacing the traditional AR15/M16/M4 gas tube, this closed system minimizes malfunctions by preventing hot carbon fouling and waste gases from entering the receiver, ensuring reliable operation. This proven technology mirrors the elite HK416 used by top-tier military and law enforcement units.

Kit Includes:

• MR556 A4 Upper Receiver/Barrel Assembly: Features an HK cold-hammer forged barrel, upper receiver with forward assist, extended convertible charging handle, and HK Free Floating Rail System handguard.
• MR556 Bolt Group Assembly: Complete bolt group for seamless integration.
• Tungsten-Filled HK Proprietary Buffer: Enhances recoil management.
• HK Proprietary Buffer (Action) Spring: Optimized for smooth cycling.
• Adjustable Gas Block: Allows for fine-tuned performance.
• HK Soft Case: For secure storage and transport.

Key Benefits:

• Converts AR-style rifles to HK’s reliable piston-driven system.
• Eliminates common direct-impingement issues for enhanced durability.
• Not classified as a firearm, so no Federal Firearms License (FFL) is required for purchase.

NFA Disclaimer: This item is regulated under the National Firearms Act (NFA). Buyers must ensure compliance with all federal, state, and local laws. For guidance on NFA regulations, consult a qualified attorney.