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 armaments of the early Panzer IV tanks and slightly modified as StuK 37 in early StuG III assault guns.
It was designed as a close-infantry support artillery gun firing a high-explosive shell (hence the relatively short barrel), but was also effective against the early war tanks it faced during the period. 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. When older Panzer IVs were upgunned, their former KwK 37 guns were reused to arm later Panzer III tanks and other infantry support vehicles. In 1943 depleted stocks and continued demand from producing Panzer III Ausf. N required restarting production of a slightly revised version under the designation 7.5 cm K 51 L/24 (7.5 cm Kanone 51 L/24).
7.5 cm KwK 37 Wikipedia
KwK 37 used shell 75×243 mm. R K.Gr.rot.Pz. - Armour Piercing Capped
Kt. Kw. K. - Canister
Nbgr. Kw. K. - Smoke
Gr.38 Hl - High Explosive Anti-Tank
Gr.38 Hl/A - High Explosive Anti-Tank
Gr.38 Hl/B - High Explosive Anti-Tank
Gr.38 Hl/C - High Explosive Anti-Tank
Projectile weight: 4.422 kg (9.75 lb)
Explosive weight: 0.454 kg (1.00 lb)
Projectile weight: 6.80 kg (15.0 lb)
Muzzle velocity: 385 m/s (1,260 ft/s)
Panzer III Ausf. N
Panzer IV Ausf. A, C, D, E, and F1
StuG III Ausf. A, B, C, D, and E
SdKfz.233 Schwerer Panzerspähwagen "Stummel"
SdKfz.234/3 Schwerer Panzerspähwagen
SdKfz.250/8 Schützenpanzerwagen (7.5 cm KwK37)
SdKfz.251/9 Schützenpanzerwagen (7.5 cm KwK37)