Pan magazine

A magazine is an ammunition storage and feeding device within or attached to a repeating firearm. Magazines can be removable (detachable) or integral to the firearm. The magazine functions by moving the cartridges stored in the magazine into a position where they may be loaded into the chamber by the action of the firearm. The detachable magazine is often referred to as a clip, although this is technically inaccurate.

Magazines come in many shapes and sizes, from those of bolt-action express rifles that hold only a few rounds to drum magazines for self-loading rifles that can hold one hundred rounds or more. Various jurisdictions ban what they define as "high-capacity magazines".

With the increased use of semi-automatic and automatic firearms, the detachable box magazine became increasingly common. Soon after the adoption of the M1911 pistol, the term "magazine" was settled on by the military and firearms experts, though the term "clip" is often used in its place (though only for detachable magazines, never fixed). The defining difference between clips and magazines is the presence of a feed mechanism in a magazine, typically a spring-loaded follower, which a clip lacks. Use of the term "clip" to refer to detachable magazines is a point of strong disagreement.

The earliest firearms were loaded with loose powder and a lead ball, and to fire more than a single shot without reloading required multiple barrels, such as pepper-box guns and double-barreled shotguns, or multiple chambers, such as in revolvers. Both of these add bulk and weight over a single barrel and a single chamber, however, and many attempts were made to get multiple shots from a single loading of a single barrel through the use of superposed loads. While some early repeaters such as the Kalthoff repeater managed to operate using complex systems with multiple feed sources for ball, powder and primer, easily mass-produced repeating mechanisms did not appear until self-contained cartridges were developed.

...
Wikipedia