The M1 Thompson was designed by American Colonel John T. Thompson and manufactured by Savage Arms Corporation in Utica, New York. When World War II started, it became clear that the previous process of making the weapon was too complicated and too expensive. The weapon's sights were drastically simplified from the original and the magazine capacity was changed from the massive 60 or 100-round drum to the more acceptable 30-round box. A 20-round box was also made available. The 'Tommy Gun' went on to achieve a tremendous amount of success, often finding favor with soldiers that preferred it over the British Sten gun and American M3 Grease Gun, which had attempted to replace the Thompson. It was no longer used in American service after the early 1960s due to technological advances.