Lewis Machine Gun The Lewis Machine Gun was a machinegun developed in the United States during the World War 1 . Even as a success in the weapons market , acting in big armies like the Russian and the English , the Lewis was mostly replaced during the World War II Description . The Lewis light machine gun was designed in USA by Col . Isaac N . Lewis , based on earlier machine gun by Dr . Samuel McLean , but found no takers because of personal opposition from US Army ’ s Chief of ordnance . Trying to sell the gun overseas , US - based Automatic Arms Co , which held patents for Lewis guns , established a subsidiary company in Belgium , know as Armes Automatiques Lewis SA . However , it was a pure marketing agent , and production contracts for first “ European ” Lewis LMG were placed in 1913 with British Birmingham Small Arms ( BSA ) company . First batch of 50 BSA - made Lewis guns was completed by mid - 1913 , in as much as seven different calibers , with obvious goal of marketing these guns across Europe . When war broke , BSA received orders for Lewis guns , and by the end of the war delivered well over 15 thousands of Lewis guns . In USA , Lewis machine guns were built in . 30 - 06 caliber , mostly for US Army Air Corps and for US Marine corps . The Lewis gun also saw extensive use as an aircraft machine gun during WW1 and in following decade . Lewis light machine gun became most famous in British use and manufacture ; it was widely used by British troops during WW1 and afterwards . During WW1 it was also supplied to Imperial Russia . During WW2 , many infantry Lewis guns were recalled from reserve stores and issued to British Home Guard units . Furthermore , in the view of possible German invasion in 1940 - 41 , many former aircraft Lewis guns , of both British and US origin , were converted for ground use and also issued to Home Guard . It must be noted that ex - aircraft Lewis guns , supplied from USA through Lend - lease program , were chambered for . 30 - 06 US Service ammunition ; when converted to ground use in UK , these guns retained its chambering and were marked with red stripes to distinguish its non - standard chambering . Lewis machine guns were also manufactured under license in Japan ( as Type 92 , for Naval infantry and aerial use ) and in the Netherlands . Lewis light machine gun is a gas operated , air cooled , full automatic only weapon that fires from open bolt . It has a non - removable barrel with aluminum radiator , enclosed into tubular barrel jacket of relatively large diameter ; jacket was opened from both front and rear . When gun was fired , the muzzle blast caused the air to flow inside the jacket from rear to front , providing forced air cooling for a relatively light barrel . In aircraft versions the jacket and radiator usually were discarded to save weight . The basic action used a rotary bolt with four radial lugs , located at the rear of the bolt ; lugs locked into the recesses in receiver walls . Bolt was operated by a vertical stud , which entered a helical cut made in the bolt body . This stud was installed on the gas piston rod , which runs below the barrel . Gas block was located near the muzzle , and was concealed within the barrel jacket . One unusual design feature of the Lewis gun was the return spring . It was a spiral , clock - type spring which operated a gear wheel , located in the semi - circular hump below the receiver . The gear wheel co - operated with a teethed rack , machined on the underside of the gas piston rod , so the return spring was wound upon recoil cycle ( under the power of powder gases ) , and then unwound itself on closing movement of the bolt group . The firing pin was fixed to the vertical stud on the gas piston rod . The feed system of the Lewis gun was also somewhat unusual , as its flat pan magazine , which held rounds in two layers , had no spring to feed cartridges into the gun . Instead , the magazine was powered by the gun itself , via special feed operating arm with two pawls , which engaged stamped ribs , made on the outside of the magazine cover . The feed arm oscillated in horizontal plane , being operated by the vertical stud located at the rear of the bolt . With each cycle of the bolt group , magazine was rotated by one step to feed next cartridge into the ready position . For aerial combat , four - layered magazines with bigger capacity were produced . Standard furniture for Lewis light machine gun included a wooden pistol grip and a wooden buttstock , and a folding , detachable bipod . Optional carrying handle could be installed near the center of gravity of the gun , that is , at the rear of the barrel jacket . Guns , converted from aerial to ground use often lacked the barrel jacket and radiator ; a light bipod was attached to the mounting , originally used to install the gun in aircraft turrets . Additionally , a skeleton buttstock was pinned to the rear spade grip and a simple rear sight set to 400 yards