The BSW 2cm FLAK is a lightweight 20 mm automatic anti-aircraft cannon manufactured in Germany in the early 1930s based on the blueprints for the Swiss Solothurn S5-100 machine gun. The weapon is also known as the 2 cm Flak m/30 or m/38. The changes to the original weapon were very small. The biggest change was the side-fed magazine. The cannon could be placed on a variety of fixed and wheeled mounts and could be moved quickly with the troops both on land and at sea. The Germans also used a special model called the Vierling, which consisted of quad-mounted cannons placed on a single carriage for increased firepower and rate of fire. The cannon was also suitable for providing fire support for infantry troops. The cannon was manufactured in very large quantities and was quickly put into service in Germany. Finland acquired at first a batch of 50 cannons just before the Winter War, and later during the interim peace and the Continuation War, hundreds of units of the slightly modernised model m/38. The upgraded model had a more advanced sighting system, it weighed 30 kg less, and the rate of fire had been increased by nearly 200 rounds per minute. An even more lighter variant, known as the Gerbigsflak 38 was also produced by Germany for the Wehrmacht and SS mountain units, but this model was not delivered to Finland.

In Finland, the automatic cannon was also known as “Gustloff”, after one of the manufacturers, Gustloff-Werke. The weapon was very popular and remained in service for a long time after the war, not only in Finland but also in Greece, Romania and Denmark, where the Wehrmacht and the SS abandoned hundreds of these cannons in the final stages of the war. The Swedish army bought 56 units in 1939. In Finland, the cannons were regularly maintained. In the 1960s they were updated with Finnish pendulum sights. In 1960, the Defence Forces still had 142 units in service. The Gustloffs were phased out in the 1990s. The best specimens were donated to Finnish military museums, and the rest were sold to various museums or collectors in Finland and abroad. The Anti-Aircraft Museum has three cannons, two of which are m/30 and one m/38.

Specifications:

calibre:        20 mm        weight: 890 kg

rate of fire: 280 rounds per minute (m/30)

range:          2200 m

muzzle velocity: 830–900 m/s

References: Vehviläinen Raimo et al., Itsenäisen Suomen Ilmatorjuntatykit 1917–2000, Sotamuseon julkaisuja I, Helsinki 2005; Palmu Pentti, Yön yli päivään – Suomen Ilmatorjunnan vaiheita 1925–1990, Ilmatorjuntaupseeriyhdistys Ry, Helsinki 1989; Ilmatorjuntamiehet Lohtajalla 1952–2002, Pääesikunta 2002