This gun is the Sten.
The Sten’s introduction was because Britain was nearly being conquered by the Nazis.The Sten was the cheapest possible gun that would work for the British.The Sten Mk I entered service in 1941 and possessed a flash hider, refined finish, and wooden foregrip and stock. Approximately 100,000 were produced before factories switched to the simpler Mk II. This type saw the elimination of the flash hider and hand grip, while possessing a removable barrel and shorter barrel sleeve. A rough weapon, over 2 million Sten Mk IIs were built making it the most numerous type. As the threat of invasion eased and production pressure relaxed, the Sten was upgraded and built to a higher quality. While the Mk III saw mechanical upgrades, the Mk V proved to be the definitive wartime model.