Developed on the basis of the KV heavy tank, the vehicle initially had very few differences from the mass-produced model. It underwent field trials in January–February 1941. Eventually, several crucial changes were made to the design, greatly boosting the combat characteristics of the vehicle. By July 22, 1941, chassis and engine development was completed. According to some sources, in the fall of 1941, the vehicle was equipped with a serial KV turret and sent to the front.
KV-3
V-5
10R
T-220
85 mm F-30
KV-3 Bis
V-2IS
10RK
85 mm S-31
107 mm ZiS-6
V-2SN
12RT
KV-3
R-113
100 mm D10T
122 mm D-2-5T
122 mm D-25T
Characteristics are specified for vehicles with crews trained to 100%.