Lewis gun
The Lewis gun is a First World War–era light machine gun. Designed privately in the United States though not adopted there, the design was finalised and mass-produced in the United Kingdom, and widely used by troops of the British Empire during the war. It had a distinctive barrel cooling shroud, and top-mounted pan magazine. The Lewis served until the end of the Korean War, and was widely used as an aircraft machine gun during both World Wars, almost always with the cooling shroud removed, as air flow during flight offered sufficient cooling.
History
A predecessor to the Lewis gun incorporating the principles upon which it was based was designed by Ferdinand Mannlicher. The Lewis gun was invented by U.S. Army colonel Isaac Newton Lewis in 1911, based on initial work by Samuel Maclean. Despite its origins, the Lewis gun was not initially adopted by the U.S. military, most likely because of political differences between Lewis and General William Crozier, the chief of the Ordnance Department. Lewis became frustrated with trying to persuade the U.S. Army to adopt his design, claiming that he was "slapped by rejections from ignorant hacks", and retired from the army.Lewis left the United States in 1913 and went to Belgium, where he established the Armes Automatique Lewis company in Liège to facilitate commercial production of the gun. Lewis had been working closely with British arms manufacturer the Birmingham Small Arms Company Limited in an effort to overcome some of the production difficulties of the weapon. The Belgians bought a small number of Lewis guns in 1913, using the.303 British round and, in 1914, BSA purchased a licence to manufacture the Lewis machine gun in England, which resulted in Lewis receiving significant royalty payments and becoming very wealthy.
Lewis and his factory moved to England before 1914, away from possible seizure in the event of a German invasion.
Production
The onset of the First World War increased demand for the Lewis gun, and BSA began production, under the designation "Model 1914". The design was officially approved for service on 15 October 1915 under the designation "Gun, Lewis,.303-cal." No Lewis guns were produced in Belgium during the war. All manufacture was carried out by BSA in England and the Savage Arms Company in the US, and although the two versions were largely similar, enough differences existed to stop them being completely interchangeable, although this had been rectified by the time of the Second World War.The major difference between the two designs was that the BSA weapons were chambered for.303 British ammunition, whereas the Savage guns were chambered for.30-06 cartridges, which necessitated some difference in the magazine, feed mechanism, bolt, barrel, extractors, and gas operation system. Savage did make Lewis guns in.303 British calibre, though. The Model 1916 and Model 1917 were exported to Canada and the United Kingdom, and a few were supplied to the US military, particularly the Navy. The Savage Model 1917 was generally produced in.30-06 calibre. A number of these guns were supplied to the UK under lend-lease during the Second World War.
Design details
The Lewis gun was gas operated. A portion of the expanding propellant gas was tapped off from the barrel, driving a piston to the rear against a spring. The piston was fitted with a vertical post at its rear which rode in a helical cam track in the bolt, rotating it at the end of its travel nearest the breech. This allowed the three locking lugs at the rear of the bolt to engage in recesses in the gun's body to lock it into place. The post also carried a fixed firing pin, which protruded through an aperture in the front of the bolt, firing the next round at the foremost part of the piston's travel.The gun's aluminium barrel-shroud caused the muzzle blast to draw air over the barrel and cool it, due to the muzzle-to-breech, radially finned aluminium heat sink within the shroud's barrel, and protruding behind the shroud's aft end, running lengthwise in contact with the gun barrel from the "bottleneck" near the shroud's muzzle end and protruding externally behind the shroud's rear end. Some discussion occurred over whether the shroud was necessary: in the Second World War, many old aircraft guns that did not have the tubing were issued to anti-aircraft units of the British Home Guard and to British airfields, and others were used on vehicle mounts in the Western Desert; all were found to function properly without it, which led to the suggestion that Lewis had insisted on the cooling arrangement largely to show that his design was different from Maclean's earlier prototypes. Only the Royal Navy retained the tube/heatsink cooling system on their deck-mounted AA-configuration Lewis guns.
The Lewis gun used a pan magazine holding 47 or 97 rounds. Pan magazines hold the ammunition nose-inwards toward the center, in a radial fan. Unlike the more common drum magazines, which hold the rounds parallel to the axis and are fed by spring tension, pan magazines are mechanically indexed. The Lewis magazine was driven by a cam on top of the bolt which operated a pawl mechanism via a lever.
In the First World War, Armourer Staff-Sargeant, Francis Leo Keeffe of the Royal Army Ordnance Corps, was awarded a Certificate of Merit for inventing an automatic filler for the gun's magazines.
An interesting point of the design was that it did not use a traditional helical coiled recoil spring, but used a spiral spring, much like a large clock spring, in a semicircular housing just in front of the trigger. The operating rod had a toothed underside, which engaged with a cog which wound the spring. When the gun fired, 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 assembly. At that moment, as the gas pressure in the breech fell, the spring unwound, turning the cog, which, in turn, wound the operating rod forward for the next round. As with a clock spring, the Lewis gun recoil spring had an adjustment device to alter the recoil resistance for variations in temperature and wear. The Lewis design proved reliable and was even copied by the Japanese and used extensively by them during the Second World War.
The gun's cyclic rate of fire was about 500–600 rounds per minute. A recoil enhancer was added to the 1918 aircraft gun variant which increased the rate of fire to about 800 rounds per minute. The ground use versions weighed 28 lb, only about half as much as a typical medium machine gun of the era, such as the Vickers machine gun, and was chosen in part because, being more portable than a heavy machine gun, it could be carried and used by one soldier. BSA even produced at least one model designed as a form of automatic rifle.
Service
First World War
During the first days of the war, the Belgian Army had put in service 20 prototypes for the defense of Namur.The United Kingdom officially adopted the Lewis gun in.303 British calibre for land and aircraft use in October 1915. The weapon began to be issued to the British Army's infantry battalions on the Western Front in early 1916 as a replacement for the heavier and less mobile Vickers machine gun, which had been withdrawn from the infantry for use by the specialist Machine Gun Corps. The US Navy and Marine Corps followed in early 1917, adopting the M1917 Lewis gun, in.30-06 calibre.
Notes made during his training in 1918 by Arthur Bullock, a private soldier in the 2/4th Oxfordshire and Buckinghamshire Light Infantry, record that the chief advantage of the gun was 'its invulnerability' and its chief disadvantages were 'its delicacy, the fact that it is useless for setting up a barrage, and also that the system of air cooling employed does not allow of more than 12 magazines being fired continuously'. He records its weight as 26 lbs unloaded and lbs loaded, and that it had 47 cartridges in a fully loaded magazine; also that it was supported by a bipod in front and by the operator's shoulder at the rear. About six months into his service, Bullock was sent on Lewis gun refresher course at La Lacque, and he recalled that the rigour of the training meant that 'everyone passed out 100 percent efficient, the meaning of which will be appreciated when I say that part of the final test was to strip down the gun completely and then, blindfolded, put those 104 parts together again correctly in just one minute.'
The gun was operated by a team of seven. Bullock was the First Lewis Gunner who carried the gun and a revolver, while 'The Second Gunner carried a bag containing spare parts, and the remaining five members of the team carried loaded pans of ammunition'. Bullock noted, 'all could fire the gun if required, and all could effect repairs in seconds'. Bullock provides several vivid descriptions of the gun's use in combat. For example, on 13 April 1918 he and his fellow soldiers intercepted a German advance along the Calonne/Robecq road, noting 'we fired the gun in turns until it was too hot to hold' and recording that 400 German casualties were caused, 'chiefly by my Lewis gun!'.
The US Army never officially adopted the weapon for infantry use and even went so far as to take Lewis guns away from US Marines arriving in France and replace them with the Chauchat LMG—a practice believed to be related to General Crozier's dislike of Lewis and his gun. The divisions of the US II Corps attached to the British Army were equipped with the gun. The US Army eventually adopted the Browning Automatic Rifle in 1917. The US Navy and Marine Corps continued to use the.30-06 calibre Lewis until the early part of the Second World War.
The Russian Empire purchased 10,000 Lewis guns in 1917 from the British government, and ordered another 10,000 weapons from Savage Arms in the US. The US government was unwilling to supply the Tsarist Russian government with the guns and some doubt exists as to whether they were actually delivered, although records indicate that 5,982 Savage weapons were delivered to Russia by 31 March 1917. The Lewis guns supplied by Britain were dispatched to Russia in May 1917, but it is not known for certain whether these were the Savage-made weapons being trans-shipped through the UK, or a separate batch of UK-produced units. White armies in Northwest Russia received several hundred Lewis guns in 1918–1919.
British Mark IV tanks used the Lewis, replacing the Vickers and Hotchkiss used in earlier tanks. The Lewis was chosen for its relatively compact magazines, but the ventilation system inside the tank caused the airflow to be reversed through the Lewis cooling jacket, resulting in hot air and fumes being blown into the gunner's face. As soon as an improved belt feed for the Hotchkiss was developed, the Lewis was replaced by them in later tank models.
As their enemies used the mobility of the gun to ambush German raiding parties, the Germans nicknamed the Lewis "the Belgian Rattlesnake". They used captured Lewis guns in both World Wars, and included instruction in its operation and care as part of their machine-gun crew training.
Despite costing more than a Vickers gun to manufacture, Lewis machine guns were in high demand with the British military during the First World War. The Lewis also had the advantage of being about 80% faster to build than the Vickers, and was a lot more portable. Accordingly, the British government placed orders for 3,052 guns between August 1914 and June 1915. Lewis guns outnumbered the Vickers by a ratio of about 3:1.