M/40 automatic cannon
The 20 mm automatkanon m/40 (akan m/40) is an autocannon with a calibre of 20 mm of Swedish origin. The weapon was intended for both anti-tank and anti-aircraft use. History

The 20 mm m/40 followed the same pattern of long-recoil operation as the 25 mm and 40 mm guns. It was chambered for a unique and quite powerful 20×145R 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 25-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 and Navy, with some 2,700 guns being produced. It was also fitted to about forty  armoured cars and to fixed AA and "combination" mountings. Operators

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20 mm artillery
Anti-aircraft guns of the Cold War
Anti-aircraft guns of Sweden
Autocannon
Firearms articles needing expert attention
Rotary magazine firearms
World War II anti-aircraft guns