Comparing: KV-4 vs. IS-3A

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.

In 1956–1957, the Military Armored Forces Academy developed a speculative design for a new loading system on the IS-3 and T-10 heavy tanks. The IS-3 variant featured a double-row ammo rack with an automatic loading system. The crew was reduced to three members: commander, gunner, and driver. The turret was redesigned in order to accommodate the loading mechanism. The vehicle existed only in blueprints.