Colt M4 to M5 Carbine Upper Receiver Kit 5.56 NATO 16.1" Heavy Barrel Black CM556-16-CK UPC 098289035455

The Colt M4 to M5 Carbine Upper Receiver Kit (Model CM556-16-CK, UPC 098289035455) is a complete factory upper receiver assembly designed to convert a standard M4-style AR-15 lower receiver into a full-featured M5 carbine. This premium conversion kit features a 16.1-inch heavy barrel chambered in 5.56 NATO and comes finished in a durable black anodized coating. Manufactured by Colt, this upper receiver kit delivers the legendary reliability, accuracy, and build quality that Colt is known for while providing the enhanced performance characteristics of the M5 platform.

Why the Colt M4 to M5 Upper Receiver Kit Stands Out

The Colt CM556-16-CK M4 to M5 Upper stands out as a genuine factory Colt conversion kit that bridges the gap between the classic M4 platform and the more robust M5 carbine configuration. The 16.1-inch heavy barrel provides increased rigidity and sustained accuracy during high-volume shooting compared to standard contour barrels. This upper receiver kit includes a complete bolt carrier group, charging handle, and handguard, allowing users to quickly and easily upgrade their existing M4 lower receiver into a more capable carbine. The heavy barrel profile helps maintain accuracy during extended firing sessions, making this kit an excellent choice for both tactical applications and recreational shooting.

Key Features of the Colt M4 to M5 Carbine Upper Receiver Kit

• 16.1-Inch Heavy Barrel: Thicker profile barrel for improved heat dissipation and sustained accuracy.
• 5.56 NATO Chamber: Compatible with both 5.56 NATO and .223 Remington ammunition.
• Complete Upper Assembly: Includes bolt carrier group, charging handle, and handguard.
• M4 to M5 Conversion: Upgrades standard M4 lowers to M5 carbine configuration.
• Black Anodized Finish: Durable, corrosion-resistant finish with a professional appearance.
• Threaded Muzzle: 1/2x28 threading ready for suppressors and muzzle devices.
• Factory Colt Quality: Built to the same standards as Colt’s military and law enforcement firearms.
• American Made: Proudly manufactured by Colt in the United States.

Ideal for Upgrading Your M4 Platform

The Colt M4 to M5 Carbine Upper Receiver Kit is an excellent choice for owners of standard M4-style AR-15 lower receivers who want to upgrade to a more capable carbine configuration. The 16.1-inch heavy barrel offers improved accuracy and heat management compared to lighter contour barrels, making it well-suited for extended range sessions and tactical training. This conversion kit allows users to retain their existing lower receiver while gaining the benefits of a heavier, more stable barrel profile. The complete assembly makes installation simple — just attach the upper to a compatible lower receiver and the rifle is ready to go. Whether you’re building a reliable home defense carbine or a versatile general-purpose rifle, the CM556-16-CK provides a factory-quality upgrade path.

This model is especially popular among builders and shooters looking for a genuine Colt upper receiver kit with a heavy 16.1-inch barrel for enhanced performance.

Premium Quality and Trusted Performance

Colt has been a leader in firearms manufacturing for nearly two centuries and is widely regarded as one of the most respected names in the industry. The CM556-16-CK upper receiver kit is built to the same exacting standards as Colt’s military and law enforcement weapons. The heavy barrel profile provides superior rigidity and heat dissipation, resulting in consistent accuracy even during sustained fire. The precision machining ensures reliable function and proper headspacing. Every Colt upper receiver kit undergoes rigorous quality control and testing before leaving the factory. The combination of the 16.1-inch heavy barrel, complete bolt carrier group, and durable black anodized finish makes the CM556-16-CK a premium choice for anyone seeking a high-quality factory Colt upper receiver conversion kit.

For builders and shooters searching for a Colt M4 to M5 Upper, Colt CM556-16-CK, Colt M5 Carbine Upper, Colt 16.1 Inch Upper, Colt Heavy Barrel Upper, Colt 098289035455, Colt M4 Upper Conversion Kit, Colt 5.56 Upper Receiver Kit, Colt M5 Upper Receiver, Colt 16.1" Heavy Barrel Upper, Colt M4 to M5 Conversion, Colt CM556 Upper Kit, or Colt 5.56 NATO Upper Receiver, the Colt Colt M4 to M5 Carbine Upper Receiver Kit 5.56 Nato 16.1 in. Heavy Barrel Black CM556-16-CK with UPC 098289035455 offers a premium factory upper receiver assembly featuring a 16.1-inch heavy barrel, complete bolt carrier group, charging handle, and full compatibility with standard M4-style AR-15 lower receivers. Experience legendary Colt reliability, enhanced accuracy, and unmatched quality with this high-performance Colt M4 to M5 Carbine Upper Receiver Kit.