The only reference I could find:
The 3.7-cm (37 mm) Model 36 and Model 37 antiaircraft gun ("Westerwald") was developed in 1938 by Rheinmetall from the precursor 3.7-cm (37 mm) Model 18 as a recoil-loader with sliding barrel and central bolt action. The barrel was 2,112.2 mm (7 ft.) long; the theoretical rate of fire was 160 shots per minute and the effective rate 80. Depending on the type of cartridge used, the muzzle velocity was 770-820 meters per second (847-902 yd./sec.). The maximum range was 6,600 meters (7,260 yd.), and the maximum ceiling 4,800 meters (5,280 yd.). The ammunition was in 6-round clips. The weapon's carriage stood on a triangular base.
Weighing 1,544 kg (3,397 lb.), the gun could be moved on the Model 52 trailer. The Model 37 was differentiated from its precursors
by its aiming sight. The 3.7-cm gun could also be installed on vehicles and buildings. After 1944 it saw action with the
self-propelled antiaircraft weapon "Ostwind," on the chassis of the Panzer IV.
popeye
