The World’s first fully automated machine guns were invented in the USA by Hiram Maxim in 1883 and patented two years later. Maxim’s machine gun saw its first use in action during the Second Boer War (1899-1902) in South Africa and the Russo-Japanese War of (1904-1905).
During WW1 forces on all sides used many machine guns, both heavy (on wheels or tripods) and light (on bipods). After WW1 machine guns became standard issue as a squad weapon for ground and anti-aircraft warfare.
The most widely used machine guns were Maxims (in many modifications), Browning’s M1919, and Hotchkiss. Between the two World Wars, there first appeared large caliber MG’s (as a rule, the caliber was .50″, or 12.7mm). The best examples – the Belgian/American Browning M2 and the Soviet model DShK-12.7mm.
In 1934 Germany released the first mass produced “Universal” machine gun, Mg34 (followed by Mg42, later – Mg43). These can be used as a ‘light’ MG on a bipod or as a ‘heavy’ one on a tripod against ground or air targets. (In the German Wehrmacht system, MG’s were designated heavy or light by usage, the caliber remained the same, as opposed to the West). The German MG’s set the trend, so almost all modern ‘medium’ MGs such as the Belgian MAG, American M60, and the Russian PKM may be used on a bipod or tripod, as needed.
Today the main role of all machine guns is to provide sustainable firepower for troops against enemy soldiers and unarmored targets. Heavy (.50/12.7mm) MG’s can also deal with lightly armored targets such as APCs, recon vehicles and helicopters.
Almost every infantry squad in the world has at least one light machine gun. A Russian squad is regularly equipped with one RPK-74 MG, a US Army squad – with two M249 SAWs. Medium MG’s are usually installed on vehicles (APC’s, Jeeps and tanks) and used by the infantry on ground mounts at troop and company level. Heavy MG’s are sometimes used as anti-aircraft weapons on tanks, main weapons on APC’s or recon vehicles and company level support weapons for the infantry.
Almost all heavy and medium MG’s, and many light ones, have quickly interchangeable barrels. Usually, every machine gun comes from the factory with one or two spare barrels, wich may be changed out in a battle environment within seconds. This feature provides the ability to sustain intensive fire for a longer period. While one barrel is being used, the spare one can be cooled – and in a pinch.. well, you can use your imagination..
Intensive heating during firing can dramatically decrease accuracy and reduce the lifetime of the barrel. In an endurance firing test of his M1919 machine gun conducted for the US military, John Browning was required to fire 1800 rounds consecutively without a stoppage; which he did, taking approximately 45 minutes to complete. The barrel became so hot that tiny droplets of liquid lead (from melting bullets) were blown back on to his hands while firing.
The feeding system of almost all medium and heavy MG’s is built around belted (or linked) ammunition. Early belts were made from textiles, modern belts are made from metal. Metal belts may be “disintegrated” or non-disintegrated.
In the disintegrated belt the metal links are connected to each other by the cartridge. When the feeding system of the machine gun removes the cartridge to feed it, the links fall apart, thus “disintegrate” the belt into pieces. In non-disintegrated belts the links are connected by the means of special details, and belts remain “in one piece” even when all of the cartridges are removed. A common belt capacity for a heavy MG is 50-100 rds, for medium and light ones – 100-250 rds.
A light machine gun often employs a magazine feeding system, using the standard ‘assault-rifle’ style box magazines for 30-45 rounds each or hi-capacity drum or dual drum (Beta-C and other) magazines for 50-100 rounds each. In light MG’s, constructed from basic assault rifle design, magazines are usually interchangeable between an LMG and an assault rifle. Good examples are the AK and RPK Russian, Steyr AUG Austrian and L85/L86 British systems. Some light MG’s such as FN Minimi/M249 are dual-feed and can use belts or box magazines without any modification.