In order to increase firepower, as well as armor thickness of KV tanks, tank KV-3 was designed. The increased chassis of the base vehicle was expected to set the conical turret with great armor thickness, armored with 107 mm gun ZIS-6 designed by Grabin V.G. The hull of the new tank with a mounted turret of serial KV-1 participated in the battles at Leningrad. Due to the war beginning, the work on the tank was stopped.