A magazine is a storage device for ammunition in a firearm. It is usually a metal cylinder, rectangular in cross-section, which fits into the grip of the firearm and holds the rounds of ammunition in position to be loaded into the barrel. The magazine spring forces cartridges up into the feeding chamber of the firearm as each round is fired. Magazines are either integral to the firearm or detachable. Some firearms have more than one magazine release button or switch, permitting more than one magazine to be loaded into and emptied from the weapon before reloading.
Different firearms have different magazine capacities. For example, a Glock 19 semi-automatic pistol has a standard magazine capacity of 15 rounds, while the extended magazine for the same model can hold up to 33 rounds.
Most magazines are designed to be disposable and can be discarded when empty. However, some high-capacity magazines are designed to be reloaded with fresh rounds of ammunition. These magazines are typically made from metal or high-strength polymer and can be very expensive.
Reloading a magazine requires some specialised equipment, such as a magazine loading tool and ammunition feeding device. It can be a time-consuming process, so it is generally only done by experienced shooters who shoot frequently.
In some jurisdictions, there are laws restricting the sale, possession, or use of high-capacity magazines. These laws generally define a high-capacity magazine as any magazine that can hold more than a certain number of rounds of ammunition. For example, California law defines a high-capacity magazine as any detachable magazine that can hold more than 10 rounds of ammunition.