A gun magazine is a detachable or fixed device that holds and feeds ammunition into the firearm’s chamber for firing. It is an essential component in most semi-automatic and automatic firearms, including pistols, rifles and shotguns. A detachable magazine typically consists of a metal or polymer housing that contains a spring and a follower. The spring exerts pressure on the follower, pushing it upwards as ammunition rounds are loaded into the chamber as the result of firing the gun.
Some firearms have fixed magazines, meaning they are part of the firearm and are not taken out to reload them. These are more common in bolt action rifles although some older semiauto rifles also had fixed magazines. Many .22 caliber rifles have fixed “tubular” magazines meaning the magazine is a tube, typically located immediately below the rifle barrel, that holds the cartridges.