Machine Gun Feeding: Spring and Hopper System

One of the main differences between different machine gun models is the loading mechanism. One popular system is the spring-operated magazine. In this system, a spring pushes cartridges in a magazine casing up into the breech. The main advantages of this mechanism are that it is reliable, lightweight and easy to use. The main disadvantage is that it can only hold a relatively small amount of ammunition.

Photo courtesy Department of Defense A U.S. Marine training with an M16A2 5.56mm assault rifle: Assault rifles, relatively lightweight, magazine-fed automatic weapons, are the gun of choice for a wide range of ground combat scenarios.

A similar system is the ammunition hopper, such as the one used in a Gatling gun. Hoppers are just metal boxes that fit on top of the machine gun mechanism. One by one, the cartridges fall out of the hopper and into the breech. Hoppers can hold a good amount of ammunition, and they're easy to reload, but they are fairly cumbersome and only work if the gun is positioned right side up.

Mounted Machine Guns Heavy belt-fed machine guns, usually mounted on a tripod or a vehicle, may need more than one operator. Individual troops usually carry light weapons, with extendible bipods or tripods for stability. Smaller automatic guns that use cartridge magazines are classified as automatic rifles, assault rifles or submachine guns. In a general sense, the term "machine gun" describes all automatic weapons, including these smaller weapons, but it also used to describe heavy belt-fed guns specifically.