A light machine gun or LMG is a machine gun designed to be employed by an individual soldier, with or without an assistant, and as a front-line infantry support. LMGs are often used as squad automatic weapons.
A light machine gun may be identified either by the weapon or by its tactical role. It is used to fire in short 8 -10 round bursts, usually from a bipod; a sustained-fire mount such as a tripod is a characteristic of a medium machine gun. Some machine guns - notably General purpose machine guns - may be deployed as either a light machine gun or a medium machine gun. As a general rule, if a machine gun is deployed with a bipod it is a light machine gun; if deployed on a tripod it is a medium machine gun - unless it has a caliber of about 10mm or larger, making it a heavy machine gun. Modern light machine guns often fire smaller-caliber cartridges than medium machine guns, and are usually lighter and more compact.
Light machine guns, such as the British Lewis, were first introduced in World War One to boost the firepower of the infantry. By the end of World War II, light machine guns were usually being issued on a scale of one per section or squad, and the modern infantry squad had emerged with tactics that were built around the use of LMGs.
It is possible to fire a light machine gun from the hip or on the move, but this is generally inaccurate. However M249 gunners report that hip firing with a mixed tracer magazine is controllable and accurate when done with a combat sling and the forward hand holding the barrel down to reduce recoil. This is said to reduce spread and make the track of the tracers more visible to the operator than they would be from behind the guns sight. The smaller 5.56mm rounds make this possible in contrast to the 7.62mm round which produces more recoil. Despite this they are usually fired from a prone position using a bipod. Many light machine guns (such as the Bren gun or the BAR) were magazine-fed. Others, such as the MG 34, could be fed either from a belt or a magazine. Modern light machine guns are designed to fire more rounds of a smaller caliber and as such tend to be belt-fed. Some LMGs, such as the Russian RPK, are modifications of existing assault rifle designs. Adaptations generally include a larger magazine, a heavier barrel to resist overheating, a more robust mechanism to support sustained fire and a bipod. Other modern light machine guns, such as the FN Minimi, are capable of firing from either an ammunition belt or a detachable box magazine.
The following were either exclusively light machine guns, had a light machine gun variant or were employed in the light machine gun role with certain adaptations.