It was designed as a close-support artillery gun firing a high-explosive shell (hence the relatively short barrel), but was also effective against the early tanks of the war. Starting from March 1942, new variants of the Panzer IV and StuG III had their main armament upgraded to the new longer-barreled 7.5 cm KwK 40. KwK 37 guns removed from older Panzer IVs which had been upgunned were reused to arm later Panzer III tanks and other infantry support vehicles.