Colt CM901

Lore & Background

The CM901 (Colt Modular) weapons system is built around a common lower receiver with an enlarged magazine well that accepts both 5.56×45mm STANAG magazines and larger-caliber ammunition via proprietary or SR-25 pattern magazines. The lower receiver features ambidextrous controls for the bolt release, magazine release, and fire selector/safety lever, along with a trigger group, pistol grip, telescopic stock, and buffer tube. Upper receiver assemblies contain the action for each caliber and are available in several barrel lengths; the 5.56mm upper has a monolithic design with a full-length top rail, three auxiliary rails, free-floating barrels, and standard flip-up sights. The lower receiver can also accept older mil-spec M16 or M16 upper receivers with an adapter.

Colt released the civilian LE901-16S in 2012, which ships with a semi-automatic lower receiver and a 410 mm (16.1 in) barrel chambered for .308 Winchester, fitted with a Vortex Flash hider. This variant accepts civilian AR-15 upper receivers and includes a magazine well adapter for smaller AR-15 magazines. The system can be anodized in standard matte black or in Desert Brown, Digital Camouflage, and Vista Camouflage finishes applied during anodizing.

In 2014, Colt Canada announced the CK901, a direct-impingement AR-AK hybrid chambered in 7.62×39mm that feeds from polymer 30-round AK-style magazines. The CK901 was first sold to the Yemeni Republican Guard in 2014, with rifles identifiable by a YEM serial number prefix. A short-barreled rifle version with a 13-inch barrel was rumored to be in development. The LE901 later served as the basis for the 7.62 version of the Modular Rail Rifle, leading to the C20 Rifle.

Reader's Guide

The Colt CM901 represents a significant step in modular rifle design, allowing the operator to change caliber and barrel length without tools, a feature that reduces downtime and logistical complexity. Its ability to accept multiple upper receivers—chambered in 5.56×45mm, 6.8×43mm Remington SPC, 7.62×39mm, and 7.62×51mm NATO—makes it adaptable to various mission roles from close-quarters battle to designated marksman tasks. The system's compatibility with existing M16/M4 controls and accessories eases training and integration for users already familiar with the AR platform. The civilian LE901 variant extended this modularity to the commercial market, while the CK901 hybrid addressed demand for the 7.62×39mm cartridge in a familiar AR-style package. The CM901's adoption by military and police forces in India, Malaysia, and Yemen demonstrates its appeal as a versatile service rifle. Its design also influenced later Colt Canada developments, including the C20 DMR, underscoring its role as a foundational modular system.

Did You Know?

• The CM901's caliber and barrel length can be changed without the use of tools.
• The civilian variant, the LE901-16S, was released on July 20, 2012.
• The system can be anodized in Desert Brown, Digital Camouflage, or Vista Camouflage finishes.