Colt M4 to M5 Commando Upper Receiver Kit 5.56 NATO 11.5" Heavy Barrel CM556-11H-CK – Premium Short Barrel Upper Assembly
The Colt M4 to M5 Commando Upper Receiver Kit 5.56 NATO 11.5" Heavy Barrel (CM556-11H-CK) is a factory-original upper receiver assembly designed to convert an M4-style lower receiver into a compact M5 Commando configuration. Manufactured by Colt, this premium upper features an 11.5-inch heavy barrel chambered in 5.56 NATO, providing excellent reliability, accuracy, and durability in a short-barreled package. This complete upper receiver kit includes the forged upper receiver, heavy contour barrel, gas system, and front sight base, making it an ideal choice for building a compact carbine or SBR (Short-Barreled Rifle) when paired with the proper lower receiver and legal requirements. The heavy barrel profile offers increased rigidity and sustained fire capability compared to standard lightweight barrels, making this upper well-suited for both professional and recreational use.
Whether you’re building a compact defensive carbine, a high-quality SBR, or upgrading an existing M4 platform, the Colt M4 to M5 Commando Upper Receiver Kit delivers authentic Colt quality and performance.
Key Features of the Colt M4 to M5 Commando Upper Receiver Kit
11.5-Inch Heavy Barrel
Heavy contour 11.5" barrel provides enhanced rigidity, improved heat dissipation, and excellent accuracy for a short-barreled platform.
5.56 NATO Chambering
Chambered in 5.56 NATO, offering compatibility with both 5.56 and .223 Remington ammunition with reliable feeding and extraction.
M4 to M5 Commando Conversion
Designed specifically to transform standard M4 lowers into the compact M5 Commando configuration favored by military and law enforcement.
Why Choose the Colt M4 to M5 Commando Upper Receiver Kit?
When searching for a high-quality, factory-original upper receiver kit to build a compact 5.56 NATO carbine, the Colt M4 to M5 Commando Upper Receiver Kit (CM556-11H-CK) stands out as a premium choice. Colt has long been recognized as one of the most trusted names in military and law enforcement firearms, and this upper receiver kit reflects that heritage. The 11.5-inch heavy barrel is a key advantage of this model. Unlike lighter contour barrels, the heavy barrel profile increases stiffness and reduces barrel whip, resulting in improved accuracy and the ability to maintain zero during sustained fire. This makes the M5 Commando upper particularly well-suited for professional applications where reliability under heavy use is critical. The M4 to M5 Commando conversion allows shooters to create a highly compact and maneuverable firearm while retaining the proven reliability of the AR-15/M4 platform. The shorter 11.5-inch barrel significantly reduces overall length compared to standard 14.5" or 16" carbines, making it ideal for close-quarters work, vehicle operations, or any situation where a compact weapon is preferred. This upper receiver kit is manufactured to Colt’s exacting military specifications. It features a forged upper receiver, properly headspaced barrel, and a gas system optimized for the 11.5-inch barrel length. The heavy barrel also provides additional material for threading should the user wish to install a suppressor or muzzle device (subject to all applicable laws and regulations). The Colt M4 to M5 Commando Upper is an excellent option for builders looking to create a high-quality SBR, a professional-grade short-barreled rifle, or a compact defensive carbine. Because it is a genuine Colt product, users can expect consistent quality, proper parts fitment, and long-term durability. This model is particularly well-suited for law enforcement professionals, military personnel, competitive shooters building short-barreled rifles, and serious enthusiasts who want authentic Colt components for their custom builds. The combination of the 11.5-inch heavy barrel, 5.56 NATO chambering, and factory M5 Commando configuration makes the CM556-11H-CK a top-tier choice for those seeking a compact, reliable, and accurate upper receiver assembly. If you’re looking for a premium Colt M4 to M5 Commando Upper Receiver Kit with an 11.5-inch heavy barrel in 5.56 NATO, the CM556-11H-CK delivers the quality, performance, and authenticity that Colt is known for.
- Colt M4 to M5 Commando Upper Receiver Kit
- Chambered in 5.56 NATO
- 11.5-Inch Heavy Contour Barrel
- Forged Upper Receiver
- Factory Gas System
- Black Finish
- Designed for Compact SBR and Carbine Builds
- Authentic Colt Manufacturing
- Model: CM556-11H-CK | UPC: 098289035479
Technical Specifications – Colt M4 to M5 Commando Upper Receiver Kit
| Specification | Details |
|---|
| Brand | Colt |
| Model | M4 to M5 Commando Upper |
| SKU | CM556-11H-CK |
| UPC | 098289035479 |
| Caliber | 5.56 NATO |
| Barrel Length | 11.5 Inches (Heavy Contour) |
| Barrel Profile | Heavy |
| Upper Receiver | Forged |
| Finish | Black |
| Key Features | Heavy Barrel, M5 Commando Configuration, Optic Ready |
| Best For | SBR Builds, Compact Carbines, Professional Use |
Shop the Colt M4 to M5 Commando Upper Receiver Kit CM556-11H-CK today.
The Colt M4 to M5 Commando Upper Receiver Kit 5.56 NATO 11.5" Heavy Barrel (CM556-11H-CK) is a factory-original upper assembly featuring an 11.5-inch heavy barrel, forged upper receiver, and M5 Commando configuration. Designed for building compact, high-performance 5.56 NATO carbines and SBRs, this premium Colt upper delivers exceptional quality and reliability. Model: CM556-11H-CK | UPC: 098289035479.
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