The release of full-fledged Soviet heavy tanks “KV-1S” began in September 1942. And in 1943 it stopped altogether. During this period, 180 such heavy tanks were manufactured. On the basis of “KV-1S” developed tanks such as “SU-152”. The Soviet heavy tank “KV-1S” is a modernized tank KV-1.   With the appearance on the front of the German army tanks “Tiger”, the question arose about the improvement of weapons.

Work on the creation of new systems was led by V.G. Grabin and F.F. Petrov. Under the guidance of V.G. The Grabin designed an 85-mm C-31 gun. And under the direction of F.F. Petrov developed 85-mm D-5T.   The C-31 gun was developed by applying an 85 mm barrel to the cradle of a 76 mm ZIS-5 tank gun. D-5T was created by using the gate and lifting mechanism from the F-34 gun.   Battle baptism of the regiment of the breakthrough was adopted on the Don and Voronezh fronts in late 1942.