Light Machine Guns (or LMG) are a class of small arms that are either adaptations of an assault rifle (generally with a larger magazine, a longer barrel, reinforced receivers, etc.), or a weapon design in its own right, chambered for an intermediate rifle (assault rifle) cartridge. Light machine guns are man-portable, and may need one or two operators. They can either be magazine-fed or belt-fed, or have the capability for both. Light machine guns usually fire from an open bolt, as this prevents rounds from cooking off due to overheating; however, there are a few exceptions to this rule, the RPK being one of them.
Most light machine gun designs also have the ability to quickly swap out the barrel, should it become overheated or a malfunction occurs that leaves the barrel damaged.
Light machine guns are used to provide suppressing fire for maneuvering purposes, usually being fired from a bipod. As a result of this, their effective range is generally greater than an assault rifle firing the same type of cartridge; hit probability is greater on an area target than aimed fire from a comparable service rifle.