The Lewis Gun was a pre-WWI era British machine gun that continued to see service all the way through WWII. It is visually distinctive because of the wide tubular cooling shroud around the barrel, and the top mounted drum magazines. The latter could hold 50 or 90 rounds.

History

It was invented by US Army Colonel Isaac Newton Lewis in 1911 but was not instantly adopted by the Americans. It was designed with an aluminium barrel casing to use the muzzle blast to draw air into the gun and cool down the internal mechanism. It could fire 550 .303 rounds per minute. The gun weighed 12 kg (28 lb), only about half as much as the monumental Vickers machine gun, and was primarily chosen because it could be carried and used by a single soldier. It was also about one sixth the cost of a Vickers, and was issued in droves to soldiers on the Western Front. (Six Lewis guns could be produced in the same time as a Vickers gun.) The lightness of the Lewis gun made it popular as an aircraft mounted weapon especially since the cooling effect of the high speed air over the gun meant that the radiator and cooling fins could be removed, making the weapon even lighter.

Col. Lewis became frustrated at trying to persuade the U.S. Army to adopt his design. He retired and headed for Belgium. The Belgians quickly adopted the design in 1913, firing the .303 British round. The Germans first encountered it in 1914 and nicknamed it 'the Belgian Rattlesnake.'

World War 1

The British quickly claimed it as their own, adopting it in late 1915. (Much like their invention of the Peabody-Martini-Henry rifle.)

The British tanks used the Lewis gun, as did British aircraft.

In 1917, the U.S. Army adopted the Lewis Gun, firing the .30-06. But the design was quickly replaced by the famous Browning Automatic Rifle or B.A.R.

World War 2

In World War Two it was replaced by the Bren gun for most infantry uses, but the Lewis saw continued service as a vehicle mounted weapon, primarily as a side gunner's weapon on aircraft. Although it was probably obsolete for that role as well, the British were facing something of a major economic crisis during the war, and had to use their existing stocks in whatever capacity made the most sense.

After WWII the Lewis was officially discontinued in British Service, and all existing models were retired in favour of the Bren, Vickers and other machine guns.