Lewis gun

Lore & Background

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 U.S. military did not initially adopt it, most likely because of political differences between Lewis and General William Crozier. Lewis left the United States in 1913 and went to Belgium, establishing the Armes Automatique Lewis company in Liège. The Belgians bought a small number of Lewis guns in 1913, using the .303 British round. In 1914, the Birmingham Small Arms Company (BSA) purchased a licence to manufacture the gun in England. Lewis and his factory moved to England before 1914, away from possible seizure in the event of a German invasion.

Production began under the designation 'Model 1914', and the design was officially approved for service on 15 October 1915 as 'Gun, Lewis, .303-cal.' All manufacture was carried out by BSA in England and the Savage Arms Company in the US. The major difference between the two designs was that BSA weapons were chambered for .303 British, while Savage guns were chambered for .30-06, though Savage also made .303 versions. The gun was gas operated, using a portion of expanding propellant gas to drive a piston. It used a spiral spring, much like a large clock spring, in a semicircular housing just in front of the trigger. The Lewis design proved reliable and was even copied by the Japanese and used extensively by them during the Second World War.

During the First World War, the United Kingdom adopted the Lewis gun in October 1915, and it began to be issued to infantry battalions on the Western Front in early 1916 as a replacement for the heavier Vickers machine gun. The US Navy and Marine Corps adopted the M1917 Lewis gun in early 1917. Some discussion occurred over whether the cooling shroud was necessary; in the Second World War, many old aircraft guns without the tubing were issued to anti-aircraft units and found to function properly without it, leading to the suggestion that Lewis had insisted on the cooling arrangement largely to show his design was different from Maclean's earlier prototypes.

Reader's Guide

The Lewis gun's significance lies in its widespread use by the British Empire during the First World War and its continued service through the Korean War. It was notable for being much lighter than typical medium machine guns of the era—about half the weight of a Vickers—allowing it to be carried and used by one soldier. Its design proved adaptable, serving as an aircraft machine gun in both World Wars, usually with the cooling shroud removed. The gun's reliability led to it being copied by the Japanese and used extensively during the Second World War. The Lewis gun also saw use by the US Navy and Marine Corps, and a number of Savage-made guns were supplied to the UK under lend-lease during the Second World War. Its legacy includes the distinctive pan magazine and the controversial cooling shroud, which some believed was unnecessary for ground use. The Royal Navy retained the tube/heatsink cooling system on their deck-mounted AA-configuration Lewis guns.

Did You Know?

• The Lewis gun used a spiral spring, much like a large clock spring, instead of a traditional helical coiled recoil spring.
• A recoil enhancer added to the 1918 aircraft gun variant increased the cyclic rate to about 800 rounds per minute.
• Armourer Staff-Sergeant Francis Leo Keeffe was awarded a Certificate of Merit for inventing an automatic filler for the gun's magazines.