7.5 cm KwK 37
The 7.5 cm KwK 37 L/24 "(7.5 cm Kampfwagenkanone 37 L/24)" was a short-barreled, howitzer-like German 75 mm tank gun used during World War II, primarily as the main armament of the early Panzer IV tank. Slightly modified as StuK 37, it was also mounted in early StuG III assault guns. It was designed as a close-support infantry gun firing a high-explosive shell (hence the relatively short barrel) but was also effective against the tanks it faced early in the war. From March 1942, new variants of the Panzer IV and StuG  III had a derivative of the 7.5 cm PaK 40 anti-tank gun, the longer-barreled 7.5 cm KwK 40. When older Panzer IVs were up-gunned, their former KwK 37 guns were reused to arm later Panzer III tanks and other infantry support vehicles. In 1943, depleted stocks and demand for the Panzer III Ausf. N required restarting production of a slightly revised 7.5 cm K 51 L/24 "(7.5 cm Kanone 51 L/24)". Ammunition. KwK 37 used shell 75×243 mm. R