When encountering difficulties on the heavily fortified Mannerheim line during the Winter War in Finland, the general staff demanded a specially equipped version fitted with a heavy howitzer, intended to deal with concrete bunkers, in support of the regular KV-1 units. But instead of choosing a more pragmatic solution of a traditional SPG, the Soviet engineers tried to get the best of both worlds in a hurry, while using the same turret ring to accommodate a fully traversable, redesigned turret to house the gargantuan howitzer. This gave the KV-2 an unmistakable profile, with its huge, towering turret, which was only accessible by a ladder. An obvious target which was also top heavy, compromising the lateral stability of the tank while crossing a sloped terrain. All these deficiencies were taken in account when the factory was relocated in the new “Tankograd” complex at the steps of the Ural. The production was no longer maintained. Only 334 were built in all from late 1939 to mid-1941.