AR15

AR-15 is a family of lightweight, magazine-fed, gas-operated rifles that originated in the 1950s with the Armalite company. The original Armalite AR-15 was designed for the 5.56×45mm NATO cartridge and formed the basis for the U.S. military’s M16 rifle family. The designation AR does not stand for “assault rifle”; it refers to Armalite Rifle. Civilian and law-enforcement variants based on the same platform are typically semi-automatic only.

In civilian use, AR-15 rifles fire one round per trigger pull and are designed around a modular action with separate upper and lower receivers and detachable magazines. The upper houses the barrel, bolt carrier group, and gas system, while the lower contains the fire-control group. Most variants use a direct gas impingement system, though piston-driven versions exist. Caliber options center on 5.56×45mm NATO/.223 Remington as the common pairing, with other calibers such as .300 Blackout and 6.5 Grendel also offered. The design emphasizes modularity, enabling a wide range of configurations with different barrels, stocks, handguards, and optics through standardized attachment platforms.

Uses and regulation: AR-15s are widely employed in sport shooting, hunting, and competitive events. They are subject to regulation that varies by jurisdiction, including restrictions on certain features, magazine capacity, and other controls in some areas. In the United States, military select-fire variants of the AR platform (the M16/M4) are restricted to military and some law-enforcement use, while civilian models remain semi-automatic.

Variants and lineage: The AR-15 name describes a broad family produced by multiple manufacturers, sharing core design elements and parts compatibility across generations.