The prototype of the KV-2 heavy tank.

On December 19, 1939, the KV-1 Heavy Tank was accepted for the service. At that time, the KV-1 took part in combat tests on the Russian-Finnish War (the Winter War). During those battles, the Soviet High Command come to conclusion that the heavy tank with more powerful armament is highly needed to combat with enemy's bunkers, pillboxes and other fortifications.

The North-Western Front HQ ordered first four KV-1 tanks from experimental party must been armed with 152 mm howitzers. To do this, the best engineers from KTZ's design bureau were summoned. After two weeks a new project was completed. In a first time engineers decided use the 152 mm mod.1909/1930 howitzer, but later it was replaced with more modern 152 mm M-10 Howitzer Model 1938/1940. A new, bigger turret was designed to accept such heavy cannon. That turret was named "MT-1".

At the beginning of 1941, the this tank was renamed to KV-2. Before this, the KV-1 called as "The Tank With a Small Turret", the KV-2 called as "The Tank With a Big Turret". The MT-1 turret was placed on the chassis of a twin-turret experimental tank instead of small turret (a large turret was also removed from the hull). On February 10, 1940, first trials were conducted. At the time, Soviet tank designers weren't very experienced in vehicles of such a heavy weight. They added a small lid on the the howitzer's barrel. That lid was intended to prevent a gun from the dust, shell's fragments and bullets. However, after the first shot this lid was torn away, after that it was never used.

A Giant and a Lilliputian. The KV-2 and the T-26 tanks.

In 1940, a pair of KV-2 were sent to the battlefront on the Karelian isthmus. In spite of some rumors, KV-2s didn't take part in battles before the Great Patriotic War. The pair of KV-2 fired on already captured pillboxes. The results of those tests were excellent and later, in 1940, a KV-2 Heavy Tank was accepted for service. Soviet tankers often called those tanks as "Dreadnoughts".

During the production, the tank's turret was slightly improved and additional DT Machine-Gun was mounted in it. The shortened M-10 Howitzer was able to fire a 52-kg high-explosive projectile with muzzle velocity of 436 m/s. Please notice, only high-explosive shells with reduced propellant charge were used for KV-2's gun. The naval semi-AP round model 1915/28 was alloed to be fired of KV-2, but that round used only in Red Navies and was absent in Red Army's warehouses. Despite some modern "sources", the usage of armor-piercing and anti-concrete ammunition was prohibited - it was recorded in the KV-2's operational manual.

The abandoned KV-2. June 1941.

The KV-2 had 36 rounds for its main gun and 3087 rounds for its bow and rear machine-guns. The crew of six crewmembers: tank commander, gun commander, second gun commander (loader), gunner, driver, and radio operator.

Besides of the 152-mm howtzer, there were some other guns which were either tested or intended to be mount on the KV-2. One of that was an attempt to mount a long barreled 106.7 mm Gun ZIS-6 (initially, this gun was proposed for the perspective KV-3 and KV-5 tanks). From May to June of 1941, the KV-2 with the ZIS-6 was tested on factory's trials, after that it was sent to the ANIOP's trials which it failed. Main problem was with gun's ammunition: the gun had single-loading rounds. Such a lond and heavy shells were wery hard to handle and operate by a single loader.