Lewis Mk 1 Light Machine Gun

The Lewis light machine gun is a gas operated, air cooled, full automatic only weapon that fires from an open bolt. It has a fixed barrel surrounded by an aluminum radiator which is enclosed in a tubular barrel jacket. The barrel jacket is open at both ends. When the weapon is fired the muzzle blast causes the air to flow inside the jacket from rear to front, providing forced air cooling for the barrel. The operating action uses a rotating bolt which has four radial locking lugs located at the rear which lock into recesses in the receiver walls. The bolt is operated by a vertical stud which enters a helical cut made in the bolt body. The stud is located on the gas piston rod and runs beneath the barrel. A gas block is located at the muzzle which is concealed by the barrel jacket. A spiral clock like spring operates a gear wheel located in a semi circular hump below the receiver. This gear wheel engages a toothed rack machined on the underside of the gas piston and cycles the bolt when the Lewis gun is fired. The firing pin is fixed to a vertical stud located on the gas piston rod. The magazine is a flat pan design which holds the cartridges in two layers. The magazine is powered by the gun by two operating pawls which engage stamped ribs located on the outside of the magazine cover. The feed arms oscillates in the horizontal plane being powered by the vertical stud located at the rear of the bolt. With each cycle of the bolt mechanism, the magazine is rotated by one notch to feed the next cartridge into the ready position. Standard furniture for the Lewis light machine gun consists of a wooden pistol grip and a wooden buttstock. A folding, detachable bipod is clamped onto the front of the barrel jacket. An optional carry handle could also be installed near the center of gravity of the gun near the rear of the barrel jacket. The receiver top plate is marked around the rear aperture sight 'Manufactured by The Birmingham Small Arms Co England' (top) with 'for Armes Automatique Lewis Belgium' (below) and LEWIS AUTO GUN MOD 1914 PAT (near the magazine). The air cooled barrel is surrounded with a cast alloy finned jacket enclosed in a two piece tubular case painted khaki. The fore sight is part of the strap that holds the two piece outer case together. The peep from the rear aperture sight is missing and a bipod is not fitted to the weapon.

The Lewis light machine gun was designed by Isaac N. Lewis who was a colonel in the United States Army. The first commercial Lewis guns were manufactured by the The British small arms manufacturer Birmingham Small Arms (BSA) Company and were initially supplied by Armes Automatiques Lewis SA which was a Belgium marketing company. At the outbreak of the First World War, BSA received orders for the mass production of Lewis guns in .303 calibre and produced over 15,000 thousand by 1918. The United States also produced Lewis guns in .30-06 calibre mainly for the United States Army Air Corps and for the United States Marine Corps. The Lewis gun saw extensive service with British and Australian forces during the First World War as a ground and aerial machine gun.