Standard Toy Soldier Poses: The BAR and :Light Machine Gun
Light machine guns found their place in World War I. Such weapons as the Lewis Gun, Chaucat and German MG08 were intended to give machine guns an offensive capability. They allowed troops to move forward and start firing almost immediately. Heavy machine guns were more defensive in nature. Moving them forward took time, several men, and required emplacing them all over again.
By World War II, most modern armies of the day had developed a light machine gun for use in their infantry platoons. The weapon was standard in the infantry squads of the United States, the British Commonwealth, France, Italy., German, Japan and Soviet Russia. Each had its own version, from the handy Browning Automatic Rifle of the Americans to the more ponderous MG 34 and MG42 of the Germans.
Some of these weapons became iconic, such as the top-loaded Bren Gun used by the British and the saucer-shaped magazine atop the Russian Degtyarev machine gun. The BAR, Bren and Degtyarev were much more portable than the belt-fed German machine guns. Soldiers armed with them Allied weapons could fire and advance at the same time. That is not as easy with a belt-fed machine gun/
Where the heavy machine gun is mounted on a large tripod, its lighter version tends to have a small bipod in front. This gives the weapon more stability. The light machine gun may be light as machine guns go, but it is heavier than the average rifle. The barrel tends to be much heavier.
Light Machine gun and automatic rifle tactics varied. German squads let riflemen pin down the enemy so the machine gun could finish them off. American squads lt the auto rifle / light machine gun provide suppressive fire while the riflemen picked them off.