The earlier Soviet KV-I with the 122mm gun needed improvement, so by ‘43 the same chassis was used for a new turret housing a 152mm gun and armor up to 4”. The tall turret was an easy target for German gunners and AT crews and could not move unless on even ground! The weight penalty of 10 more added tons wore out the 550 hp diesel engine and transmission. This tank was burdensome on the fluid battlefield of the late war years but was kept on for its good reputation as a SPG (Self-Propelled Gun) during urban assaults where the gun was devastating. Two versions were built but a third design for further upgrades was a non-starter. A German Tiger could take this out at 1400m range while the KV-II had to close to 500m to kill a Tiger. The Soviets moved on with the T-85 and 100 tanks that became the IS-1 and then on to the IS-2 and IS-3 that could match the Tigers pretty well. IS-3s, however, never saw combat in WW2 but were used in post VE-Day parades.