AR15M16M4

The AR-15, M16, and M4 refer to a family of shoulder-fired rifles and carbines that share the AR (Armalite Rifle) platform. Originally developed by the Armalite division of Fairchild in the 1950s and later produced by Colt and other manufacturers, the design has been adapted into both civilian and military variants. The term AR-15 is commonly used for the semi-automatic civilian/multi-purpose version, while M16 and M4 designate military configurations designed for select-fire or fully automatic operation in some models.

Core features of the family include a staggered, detachable magazine feeding a gas-operated action, usually direct impingement in most commercial versions, and a modular upper and lower receiver system. The platform is typically chambered in 5.56x45mm NATO (with .223 Remington compatibility in some barrels or with specific chambers) and commonly uses STANAG magazines. The system supports a wide range of accessories and optics through standardized rails and mounting points, contributing to its modularity across variants.

Variants and key differences:

- AR-15: The civilian semi-automatic version, designed for general use and sport shooting. It is widely available in multiple calibers, with extensive customization options and aftermarket parts.

- M16: The United States military’s original select-fire rifle derived from the AR platform. Variants include M16A1, M16A2, M16A3, and M16A4. Early models featured different handguards and a carrying handle; newer iterations emphasize modular rails and improved sights, with some models retaining burst-capable or semi-auto configurations.

- M4 carbine: A shorter, carbine-length variant with a 14.5-inch barrel and a telescoping stock, designed for higher mobility. The M4 family, including the M4A1, commonly employs a flat-top upper, rail systems, and is standard issue in many armed forces.

The AR-15/M16/M4 family emphasizes modularity, standardized ammunition compatibility, and a long service history across civilian and military contexts.