Staff Writer (Updated: 9/4/2015):
For some time, Soviets were attempting to mate a variety of big guns to tracked hulls. The KV-2 was something of a success in that respect and was fielded to good effect against the Finnish Army during "Winter War". However, by the time the tank was thrown at the German Army - a much more studied, experienced and prepared group of soldiers with excellent anti-tank weapons and doctrine - soon shown the limitations of the KV-2 system to a high degree.
A limited set of early KV-2 vehicles were fitted with the 122mm M1938 L/22.7 (4.8 inch) howitzer but this was eventually "upgunned" to become the more noted 152mm M1938 L/24.3 (6 inch) caliber weapon. The 152mm gun became the largest caliber weapon ever fitted to a serial production tank. In either case, the armament required a large, powered turret structure for which the crew could manage its functions and recoil while in relative safety from battlefield dangers and the elements. In this respect, Soviet engineers did not disappoint, creating an ugly, box-like, 12-ton turret sporting 360-degree traversal and some 3 inches of armor protection. Elevation was available though limited to 37 degrees. One of the key inherent deficiencies in the KV-2 design proved to be the lack of attention given by Soviet engineers to this turret when added to the existing KV-1 hull - engine output power was not addressed to compensate for the added weight, resulting in a tank that was much heavier than its sister and would suffer mechanically, functionally and performance-wise as a result. Additionally, it could not manage certain critical travel areas such as roadway bridges that other tank classes could.
Outwardly, the KV-2 was of a most distinct design, quite a departure from previous and future Soviet tank offerings. The type sported a running length of over 22 feet, a width nearing 11 feet and height of nearly 12 feet. Power was supplied by a single V-2K 12-cylinder diesel-fueled engine of 550 horsepower. The vehicle was crewed by no fewer than six personnel including the driver, tank commander, gunner, loaders and machine gunners. Primary armament was the 152mm M-10 main gun, this backed by 3 x 7.62mm DT machine guns - one fitted coaxially in the turret, another in the front-left hull next to the driver and the other in a rear-facing position at the back of the turret to prevent infantry attacks. 36 x 152mm projectiles were afforded to the gunnery crew. The gun was cleared to fire a High-Explosive (HE) and Armor-Piercing (AP) round at 952 feet per second and 1,667 feet per second, respectively, out to ranges of 13,500 yards. 3,087 rounds of 7.62mm ammunition were carried aboard for the various machine guns. Overall, the vehicle weighed in at 45 tons - becoming one of the heaviest tanks of its time. Armor protection could range up to 110mm in thickness and top speed was an inadequate 16 miles per hour, road ranges limited to 110 miles.