Comparing: Kirovets-1 vs. KV-5

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.

Development began in June 1941 at the Leningrad Kirov Plant and was completed by August, but plans were interrupted due to the complicated situation on the front. The KV-5 was to utilize some components of the KV-1. A new turret was designed, incorporating the 107-mm ZIS-6 gun. Two roadwheels and a single support roller were to be added on each side. A new 1,200 h.p. diesel engine was being developed for the vehicle, however it was not completed in time and was replaced with two V-2K engines.