Light machine guns were originally developed to support infantry squads, by providing short bursts of suppressive fire, designed to keep the enemy's heads down and allow friendly soldiers to advance. The first light machine guns were developed around World War I. Early machine gun examples include the Browning BAR M1918, Lewis gun, Madsen machine gun etc. In present day military forces, many infantry units carry one LMG per fire team or squad.
Browning Automatic Rifle (BAR) M1918, designed during World War I. Click on the image to enlarge. Public domain image.
A Lewis gun. Click on the image to enlarge. Public domain image.
The word "light" is a bit of a misnomer, because most LMGs are heavier than the assault rifles that the rest of the team carries. However, they are lighter than the other classes of machine guns that we are going to study in the following posts.
Light machine guns are generally designed to use the same ammunition as the rifles carried by the rest of the unit. This feature allows the different soldiers to share ammunition during a battle. For instance, the Browning M1918 uses .30-06 ammunition, the same as the M1903 rifle carried by US soldiers in World War I, the M249 SAW uses the same 5.56x45 mm. ammunition used by M16 rifles etc. Since LMGs are designed for automatic fire, many feature high capacity magazines, such as drum magazines, pan magazines or ammunition belts. However, some models of LMGs are designed to use the same box magazines as the assault rifles carried by the rest of the unit, so that they can share both magazines and ammunition between themselves. Some newer LMGs are designed to use multiple methods of feeding ammunition. For instance, the FN Minimi, the M249 SAW, IMI Negev and the Heckler & Koch MG 43 (now known as the MG4) are designed to use both ammunition belts, as well as box magazines. This allows the machine gunner maximum flexibility in using ammunition and magazines during a battle.
A M249 equipped with an ammunition belt. Click on the image to enlarge. Public domain image.
While the LMG is light enough to be carried by a single soldier and fired from the hip, it is generally fired from the prone position. Because of this, many LMGs have a bipod attached to the front of the barrel, to allow the user to comfortably operate the weapon from the prone position.
In recent times, many LMGs are modifications of an existing assault rifle design. Examples of these include: RPK (Russian LMG design based on the AK-47), Steyr AUG LMG (Austrian rifle based on the Steyr AUG rifle family), INSAS LMG (Indian rifle based on the INSAS rifle family) etc. However, the LMG versions are generally designed with longer and heavier barrels, to sustain automatic fire for longer periods of time without overheating. Some models (such as the Steyr AUG LMG) have quick change barrels to solve the overheating problem. The parts of the action are also designed to be more robust than the assault rifle versions, in order to shoot in full automatic mode for longer periods of time.
An INSAS Light Machine Gun. Click on the image to enlarge.
A Bren gun. Public domain image.
The above image shows a Bren gun Mark I. Note the curved box magazine mounted on top of the rifle and the carrying handle in the middle of the gun, which also doubles as a tool to remove a hot barrel. Later models came with heavier chrome-lined barrels, which reduced the need to interchange barrels. The Bren gun was first adopted in 1938 by the British, produced by various commonwealth countries (UK, Australia, Canada, India) over the years and is still being manufactured currently in India!
The Madsen machine gun also has a long history, being originally manufactured by Denmark in 1902 and still going strong in the hands of Brazilian military police, well into the 21st century! It just goes to show that good designs can last a really long time.,
In our next post, we will study another class of machine guns: the heavy machine gun.