The STEN gun was a British submachine gun used during World War II. It was designed in 1940 by Major Reginald V. Shepherd and Harold J. Turpin, and was manufactured with both a simple and cost-effective design. The STEN gun was made from inexpensive materials such as steel tubing and sheet metal, and was capable of firing up to 500 rounds per minute. It was widely used by British forces during the war, and was also adopted by other Allied forces.