Lewis Gun

The Lewis Gun was a pre-WWI era American design of machine gun most widely used by the British Empire and Imperial armies that continued to see service all the way through to WWII, it first saw combat with the Belgian Army in WWI. It is visually distinctive because of the wide tubular cooling shroud around the barrel, and the top mounted drum magazines.

History

The Lewis gun or Lewis Automatic Machine Rifle was invented by US Army Colonel Isaac Newton Lewis in 1911 but was not instantly adopted by the Americans. This may have been due to a clash of personalities with the American selection officer. It could fire 550 .303 rounds per minute. The gun weighed 12 kg (28 lb), only about half as much as a typical machine gun of the era such as the Vickers machine gun, and was primarily chosen because it could be carried and used by a single soldier. It was also relatively cheap at about one sixth the cost of a Vickers, and was issued in droves to soldiers on the Western Front. In total only 62 parts made up the gun. (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.

Design

The Lewis gun was gas operated. A portion of the expanding gases was tapped off from the barrel. This drove a piston to the rear against a spring.

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. There is some discussion over whether the cooling tube was effective or even necessary - in the Second World War many old aircraft guns which did not have the tubing were issued as anti-aircraft units for the British Home Guard and UK airfields, and were found to perform just fine without the tube. Later, more aircraft guns were used on vehicle mounts in the heat of the Western Desert and again did not suffer without the tube. The Royal Navy, however - ever a bastion of tradition - insisted all their Lewis guns had to retain the tubing, even in the cold of the Arctic (!).

The drum magazines could hold 47 or 97 rounds (the picture below shows the 47 round version). The 97 round magazine was designed for aircraft use and was considered too heavy for infantry use. A few Lewis guns were issued for anti-aircraft use with the 97 round drums by the British Army in 1916, but the big drum did not stand up well to the arduous conditions of trench warfare and the 47 round was used thereafter. The aircraft types of magazine had to be carefully stored when used with ground mounts as the underside was open and exposed the ammunition to dust, dirt or spray, which was then carried into the gun mechanism. Interestingly, the Lewis was considered very reliable despite this design fault, but then this may have been in comparison to other less reliable designs like the notorious Chauchat.

An interesting point of the design was that it did not use a traditional longitudinal coiled spring, but used a spiral spring, much like a big clock spring, in a semi-circular housing just in front of the trigger. The bolt had a toothed underside, which engaged with a cog which wound the spring. When the gun fired a round, the bolt recoiled and the cog was turned, tightening the spring until the resistance of the spring had reached the recoil force of the bolt. At that moment, as the gas pressure in the breech fell, the spring unwound, turning the cog, which, in turn, wound the bolt forward for the next round. As with a clock spring, the Lewis gun's recoil spring had an adjustment device to adjust the recoil resistance for variations in temperature and wear. Unusual as it seems, the design proved enduringly reliable.

Service

Colonel 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. Not long after that the Birmingham Small Arms Company (BSA) purchased a licence to make it. The Germans first encountered it in 1914 and nicknamed it "the Belgian Rattlesnake".

World War I

The British quickly claimed it as their own, adopting it in late 1915. (Much like their invention of the Peabody-Martini-Henry rifle.) Each Lewis gun required a team of two gunners, one to fire and one to carry ammunition and reload, and the whole rifle squad was trained to fire it in case the gunners were incapacitated.

The early British Mark IV tanks used the Lewis gun. It was used on British aircraft either as an observers or gunners weapon or as an additional weapon to the Vickers machine gun.

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 II

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.

In the crisis following the Fall of France, Lewis guns were used to arm the British Home Guard.

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.

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