Development started at the end of 1938. A prototype was produced in August 1939. The vehicle first saw combat in December 1939 at the Mannerheim Line. The tank was mass-produced from March 1940 through August 1942, with a total of 2,769 vehicles manufactured.
Time for the successive autoreloading of each shell into the magazine.
Characteristics are specified for Siege mode.
The technical characteristics are displayed for the charged turbine mode.
Characteristics are specified for Rapid mode.
Reload time of the first and second guns on double-barreled vehicles.
Characteristics are specified for vehicles with crews trained to 100%.