How do assault-rifle magazines feed ammunition into a weapon?

Assault-rifle magazines function as storage devices that hold metallic cartridges in a spring-loaded configuration. These magazines are typically designed as box-style containers that keep the ammunition ready for the weapon's action.1

To feed the ammunition into the chamber, the rifle utilizes a mechanical system—such as a bolt or a semiautomatic mechanism—to extract a single cartridge from the magazine and move it into the breech. Once a round is fired, the automatic rifle uses either the energy from the recoil or a portion of the propellant gases to eject the spent case, load the next cartridge from the magazine, and cock the weapon for the subsequent shot. This cycle continues automatically as long as the trigger is held down and the magazine contains ammunition.12