Developed in 1945 on the basis of the IS-2 and IS-3 vehicles, under the supervision of Joseph Kotin. One of the distinctive features was the slope angle of armor plates. Passed trials successfully, but never entered service.
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%.