A magazine is a device which both stores and assists in the feeding of ammunition through the use of a mechanical (usually spring-loaded) follower. It derives its name from the ammunition storage area of warships and military facilities.
A device for containing a belt is not a magazine: it is usually referred to as a belt box or ammo can, or a drum (not a drum magazine) on smaller examples.
Integral magazines cannot be removed from the weapon easily, and if detachable at all are only capable of being removed to assist in cleaning and maintenance. They are generally loaded with individual rounds or stripper clips.
Detachable magazines come in various shapes, sizes, capacities and stacking styles. Capacities can range anywhere from one to over a hundred rounds depending on the ammunition and magazine type.
In box magazines, the cartridges are stored in parallel columns, or "stacks". The most common types are single column and double column. Casket magazines may have more than two.
Single column magazines are usually found on pistols.
Double column magazines have the rounds staggered in order to fit more rounds into the magazine and still keep the magazine relatively compact.
Single feed is found on all single-column and some double-column magazines. It is mostly found on pistol magazines. The magazine's lips are only wide enough to fit one cartridge through. Double-column, single-feed magazines have historically had reliability and reloading problems due to the issue of channelling rounds from the staggered column into a straight line.
Double feed denotes a type of magazine whose feed lips are wider, to the point where almost two cartridges can fit through. The second cartridge pushes the first cartridge against one of the feeding lips. Any top cartridge can be fed into the bolt from the opening, irrespective of what lip the cartridge is pushed against.
This type of magazine is extremely common on shotguns and common on older rifles, particularly lever action rifles. Rounds are pushed into the tube against the follower, with each round pushing the previous one further into the tube. Ceased to be used on rifles following the widespread adoption of pointed bullets, as these could cause loading issues when the point of one bullet pressed the primer of the previous one. Tubular magazines are usually integral, though some weapons like the SRM Arms Model 1216 have detachable tubular magazines.
Box magazines store cartridges in columns. They can be either detachable or integral.
- An integral box magazine (also known as a fixed magazine) is a magazine that is built into the firearm and cannot be removed without dismantling the weapon. This type of magazine is usually found on bolt-action rifles. Rounds can be either loaded individually by hand, or fed by stripper clips, which make reloading faster. En-bloc clips can also be used by some weapons.
- A detachable box magazine can be detached and inserted easily into a firearm via its magazine well. With modern production controls, magazines can be produced in a standard size, allowing quick replacement of an empty magazine with a loaded one. Detachable magazines can either be straight or curved, depending on the shape of the cartridge. Common materials for a detachable magazine include metal or plastic (or a combination of the two), the latter of which may be transparent or translucent, to aid in keeping track of remaining rounds. Additionally, physical openings can be made to the magazine to serve as a "window" to count ammunition.
A casket magazine is a widened box magazine. They have four columns, or rather, a pair of double columns that feed into the same opening. The Spectre M4 can take 50-round casket magazines. 100-round STANAG-compatible casket magazines are also in production by the company Surefire, and Izhmash has developed a 5.45×39mm casket magazine for the AK-12.
A rotary magazine (also known as a spool magazine) consists of a star-shaped, rotating sprocket. They can be either fixed or detachable, with the cartridges sitting in between the grooves of the sprocket. The sprocket indexes via a torsion spring. Rotary magazines are very compact length-wise, but are of course, wider, and do not hold as many rounds as a conventional box magazine. Examples of firearms that use rotary magazines are the M1941 Johnson rifle and the Steyr SSG 69, which use fixed and removable magazines, respectively.
A pan magazine stores cartridges in a flat radial arrangement. The rounds rotate around the axle of the pan when feeding, with the rotational force usually provided by some component of the gun's action. The Lewis Gun, Degtyaryov machine gun and the American-180 use pan magazines.
A drum magazine stores rounds in a circular track around the outside of a rotating follower assembly. A snail drum instead stores the rounds in a spiral, while a double drum has two circular tracks that alternate feeding into a central feed column. A saddle drum is a subtype of double-drum which is mounted on top of the weapon's action.
A drum magazine is distinct from a drum, which has no mechanical follower and is a type of belt box.
Helical magazines are essentially elongated drum magazines. The cartridges, as one would expect, are stored in a spiral configuration. A rotating follower, known as a drive member, indexes the rounds for feeding. This design increases a magazine's capacity while retaining relative compactness of the firearm, though it imposes restrictions on the weapon's layout and can be mechanically unreliable. This magazine is used on the Calico and PP-19 Bizon submachine gun.