Comparing: IS-6 vs. Kirovets-1

Plans for this vehicle were drawn up in the construction bureau of the Chelyabinsk Kirov plant from December 1943 to the summer of 1944. Further development and the construction of the first prototype took place at the Uralmash plant. However, the vehicle had no advantages over the other heavy tank designs under consideration, and its armor was seen as inferior to the IS-4 (Object 701), so the IS-6 was not selected for production.

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.