M16

The M16 is a family of military rifles developed in the United States, derived from the ArmaLite AR-15 design by Eugene Stoner. It is chambered for the 5.56x45mm NATO cartridge and has been produced by Armalite and Colt (and its successors). Adopted by the U.S. military in the 1960s, it became one of the most widely used small arms in the world and has been issued to numerous allied forces.

Design and mechanism

The M16 is a lightweight, gas-operated, air-cooled, magazine-fed rifle. Most early models use a direct gas impingement system, where gas from firing cycles travels through a gas tube to cycle the action. The platform is typically arranged with an aluminum receiver and interchangeable furniture, and it feeds from removable box magazines that commonly hold 20 or 30 rounds. The rifle is designed for semi-automatic fire in later variants or selective-fire in early versions, depending on model.

Variants and evolution

The M16 family has undergone several major variants. The original M16A1 saw widespread combat use in the Vietnam era. The M16A2 introduced improved sights, a heavier barrel, enhanced ergonomics, and a 3-round burst mechanism. Later variants such as the M16A3 and M16A4 added flat-top upper receivers to facilitate optics mounting, with the A4 incorporating full-length rails to support modular optics and accessories.

Operational history and use

The M16 has been used by the United States and many allied forces in multiple conflicts since the 1960s. It is valued for its light weight, standardized ammunition, and ease of use, but has required regular maintenance to prevent reliability issues in dusty or harsh environments. Its role has diminished in front-line U.S. service in favor of newer platforms, though it remains in service in some countries and in various forms around the world.

Legacy

As a foundational design, the M16 influenced many subsequent rifles and led to widespread adoption of 5.56mm, lightweight, modular rifle concepts. It remains a historically significant and widely recognized small arm.