Heckler & Koch presents the MR556 A4 Upper Receiver Kit, a pinnacle of engineering excellence. This kit features a 16.5" cold hammer-forged barrel, an adjustable gas block, and an M-LOK handguard, ensuring superior performance and reliability. Designed for ease of use, it seamlessly integrates with AR-15 lower receivers, offering a piston-driven system that minimizes malfunctions.

Ideal for range time and training, the MR556 A4 Upper Receiver Kit is a testament to HK's innovation and quality. It provides a reliable platform for a wide variety of 5.56mm or .223 ammunition, making it a versatile choice for enthusiasts. HK's reputation for precision and durability is unmatched in the industry.

Key Features:
- Manufacturer: Heckler & Koch
- Model: MR556 A4
- Caliber: 5.56 NATO
- Barrel Length: 16.5"
- Adjustable Gas Block: Yes
- M-LOK Handguard: Yes
- What's In The Box: Bolt Carrier Group, Charging Handle, Buffer Weight, Buffer Spring
- Optics Ready: Yes