20 х 138 mm B Rheinmetall-Solothurn
20 х 138 mm B Rheinmetall-Solothurn – in the 1920s, the German company Rheinmetall Borsig AG bought the Swiss munitions factory Solothurn Waffenfabrik AG in order to develop new weapons and ammunition that were restricted to Germany by the Versailles Treaty. In 1930, this Swiss munitions factory developed a new 20 x 138 mm B cartridge for German anti-aircraft and anti-tank guns. The "B" in the name stands for belted, i.e. a protruding strip on the bottom of the cartridge. This cartridge was specially developed for the German 2 cm Flak 30, later 38, anti-aircraft guns. Eventually the 2 cm KwK 30 and later 38 tank guns. In addition to the Germans, the Italians, Swiss, Finns and Poles also used this cartridge for their anti-aircraft guns. The cartridge was produced in Germany, Italy and Finland. The cartridges found by Silesian Museum are unfortunately made of steel and therefore no stamping has survived on any of them.