20×138mmB

Type of ammunition

The 20×138mmB or Long Solothurn cartridge is a type of ammunition used mainly for anti-aircraft and anti-tank weapons during World War II. The designation means the caliber is 20 mm, the length of the cartridge case is 138 mm and B indicates it is a belted case. The loaded cartridge weighs 300 grams (10.7 oz).^[1]

History

Three Finnish and Italian 20×138B cartridges next to a 37mm anti-tank shell

The 20×138mmB cartridge was developed by the Waffenfabrik Solothurn [de], a Swiss front company of Rheinmetall in the early 1930s from a less powerful cartridge 20×105mmB cartridge.

Weapon platforms

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

Switzerland

• Solothurn anti-tank rifles: S-18/1000 and S-18/1100
• Solothurn ST-5 20mm AA Gun

Germany

• FlaK 30 and FlaK 38 single-barrel, and Flakvierling quadruple-barrel anti-aircraft guns
• KwK 30 and KwK 38 vehicle-mounted weapons
• MG C/30L aircraft gun

Italy

• Cannone-Mitragliera da 20/65 modello 35 (Breda)
• 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

References

1. Johnson, Melvin M. Jr. (1944). Rifles and Machine Guns. William Morrow and Company. p. 385.