M/40 Automatic cannon

The 20 mm maskinkanon M.40 S is a heavy machine gun with a calibre of 20mm of Swedish origin. The weapon was intended as both an anti tank and anti aircraft weapon.

History
The 20mm m/40 followed the same pattern of long-recoil operation as the 25mm and 40mm guns. It was chambered for a unique and quite powerful 20x145R cartridge, and could fire at 360 rpm. On a wheeled AA mounting, it weighed 300 kg, on a low tripod for anti-tank use, it weighed 65 kg (the same gun was used in both installations, and could be switched between mountings). In anti tank form, it was given the nickname "grasshopper" as it jumped about so much on firing. It was known as the PansarVärnsLuftVärnskanon m/40 (PVLV) which translates as "Anti-tank/anti-aircraft gun". The ammunition feed consisted of an exposed 28-round rotary magazine above the gun, which in the AT mounting meant that the sights had to be fixed to the side. It appears that these weapons were only used by the Swedish army, with some 2,700 guns being produced. It was also fitted to about forty PB m/31 armoured cars and to fixed AA and "combination" mountings.

The 20mm m/45 and m/49 were quite different, being short-recoil guns chambered for the 20x110 HS 404 cartridge, which was ordered in the 1930s but not accepted for service until after World War II. Their development was prompted by concern about the difficulties in importing weapons in wartime so it was decided to make an indigenous design to meet the needs of the rapidly growing Swedish Air force. Size, weight and rate of fire were all quite similar to the Hispano HS 404, and in fact the French gun was also in service with the Swedish air force during the 1940s. The Bofors guns saw service in some of the early Swedish jet strike/ground-attack aircraft, the SAAB A21 and A32A respectively. They may also have armed the Pbv 301 and Pbv 302 IFVs from the late 1950s.