20×138mmB

The 20×138mmB cartridge or Long Solothurn was a type of ammunition used mainly for anti-aircraft and anti-tank weapons during World War II. The designation means the caliber was 20 mm, the length of the cartridge case was 138 mm and B indicates it was a belted case. The loaded cartridge weighed 10.7 oz.

History
The 20×138mmB cartridge was initially created by the Swiss Solothurn company in the early 1930s.

Users
The 20×138mmB cartridge was used in the following weapons:

Switzerland

 * Solothurn anti-tank rifles: S-18/1000 and S-18/1100

Germany

 * FlaK 30 and FlaK 38 anti-aircraft guns
 * KwK 30 and KwK 38 vehicle-mounted weapons
 * MG C/30L aircraft gun

Italy

 * anti-aircraft guns: Cannone-Mitragliera da 20/65 modello 35 (Breda) and Cannone-Mitragliera da 20/77 (Scotti)

Finland

 * Lahti L-39 anti-tank rifle
 * Lahti L-40 anti-aircraft gun

Poland

 * Nkm wz.38 FK anti-tank vehicle mounted gun