Comparing: KV-4 vs. Kirovets-1

The project of N. L. Dukhov developed in April 1941. A prototype was to be produced by November 1941. However, the work was discontinued due to the outbreak of the Soviet–German war.

The Kirovets-1 project (IS-3, prototype No. 1) was developed from July through November 1944. The prototype was built at the Chelyabinsk Kirov Plant in September–October 1944. From December 18 through December 24, 1944, the vehicle underwent trials at the NIBT proving grounds in Kubinka. After it was decided to manufacture a pilot series of the modified IS-2 with a hull proposed by engineers of Plant No. 100 and Сentral Research Institute-48, the work on the Kirovets-1 was discontinued.