M75 testing continued into 1942. By that time, however, there was no longer a need for the antitank monsters. The super-heavy German tanks had not materialized, and, in addition, the actual M75 parameters did not meet requirements for a variety of reasons. Work on the gun was put on hold, but it came up again in 1943 when the heavy German tanks eventually made it to the front.
In contrast to the 107 mm SP gun, the B-13 project with the 130 mm gun was listed in GAU development plans dated May 22, 1941. A proposal in 1941 called for production of 12 SP guns of that type, at a cost of 300,000 rubles each. The specifications for the SU-B-13 can be found both in a letter written by Kulik and in a draft operational requirement dated June 16, 1941:
I. General characteristics.
1. Vehicle type: tracked, armored
2. Total weight: 55 tons
3. Armament: the B-13 130 mm gun and 3 DT machine guns
4. Combat load: rounds for the gun, 100
- Machine-gun rounds: 2500
- Hand grenades: 30
5. Armor:
- Glacis: 30 mm
- Side: 30 mm
- Top: 30 mm
- Bottom: 20 mm
6. Crew: 7
7. All of the vehicle’s remaining dynamic characteristics and its mobility are to be the same as the KV-4 tank. The engine mount, transmission, and suspension system must be the same as those used on the KV-4.
8. The vehicle’s dimensions must allow shipment by rail.
9. SU-B-13 artillery system specifications:
a) The artillery system must be installed on a production chassis without a turret, and the crew must be protected against diving aircraft.
b) The angle of traverse must be at least +/-10°.
Elevation +20° to 25°
-2° to -3°
c) The layout of the artillery system, aiming devices, and ammunition rack must enable at least three aimed shots per minute.
d) The vision devices must provide good visibility from the vehicle, and a commander’s cupola enabling 360° vision must be installed.
e) The vehicle must support firing from cover.
f) The artillery system must have a means of securing the gun in travel position.
10. Communications equipment:
a) A KRSTB radio must be provided for external communication. A TPU-4 intercom system must be installed for internal communication.
b) Provide for stowage of 2 telephone sets and 2–3 km of wire.{10}
Unlike the 212, the SU-B-13 was not a bunker buster. The specifications clearly describe a heavy tank destroyer that was developed in a rush to combat German heavy and super-heavy tanks. This is clearly evident from the rate-of-fire requirement and the requirement for 30 mm of armor, the same armor thickness as on the SU-34 tank destroyer based on the T-34 and the A-46 tank destroyer based on the A-42 prime mover, which were developed by Kalinin Factory No. 8 (in Kaliningrad, a city now named Korolev). The identification of the KV-4 as the base chassis is an error. Records show that this is what Kulik called the KV-3 (Project 223), confusing it with the KV-3 (Project 150, or the T-150), which originally was supposed to go into production. Because the Great Patriotic War began a week after the operational requirement was drafted, the SU-B-13 did not make it past the conceptual design stage.
CHAPTER 3.
The Evacuation
The tank programs underwent a fundamental revision immediately after Germany attacked the Soviet Union. The manufacture of armored vehicles already in production was accelerated, and programs that were in the design stage or that did not conform to wartime realities were shut down. The most common theory has it that Project 212 met a similar fate, but its actual history was somewhat different.
Under Order No. 253ss issued by the People’s Commissariat of Heavy Machine Building on June 26, 1941, preparations for production of the KV-3 were transferred from the Kirov Factory to the Chelyabinsk Tractor Factory (ChTZ). Chelyabinsk received a team of designers from the Kirov Factory, as well as production engineers, materials, and the KV-3 prototype minus its turret and a number of other assemblies. As of February 1942, this KV-3 was located in experimental shop OP-2. But Project 212 continued to be listed as a Kirov Factory project until early August 1941, as evidenced by a letter GAU Deputy Director Lt. Gen. V. I. Khokhlov wrote on the 11th to V. A. Malyshev, People’s Commissar of Medium Machine Building:
According to Government Decree (No. 274-130ss, dated February 7, 1941), the Kirov Factory is to manufacture a batch of 10 BR-2 152 mm self-propelled guns based on the KV-3 tank.
It has not yet begun manufacturing the systems, and the contract sent by the Director has not been signed. According to a statement by Comrade Bondarenko, Kirov Factory’s chief engineer, the factory will not manufacture the vehicles due to the press of other work.
Please inform me who authorized the withdrawal of production of these vehicles from the Kirov Factory.{1}
It was only in late August 1941 that SP gun Project 212 was transferred to the Ural Heavy Machinery Plant (abbreviated UZTM and located in Sverdlovsk, now named Yekaterinburg). The choice of UZTM as the site where work on the bunker buster would continue was no accident. The giant Sverdlovsk factory was the main supplier of KV-1 armored hulls for the Chelyabinsk Tractor Plant. Equally important was that, as the war began, UZTM’s design Bureau had a wealth of experience in the design and manufacture of howitzers and corps-level artillery. The factory’s design bureau under V. N. Sidorenko had developed the U-1 howitzer in 1937, and in 1938, it had developed the U-2. The following year, it developed the U-3 203 mm corps-level heavy howitzer. The decision was made in 1940 to engineer production of the M-30 122 mm howitzer at UZTM, and its creator, Fedor Petrov, traveled to Sverdlovsk for that purpose. Fedor’s business trip lasted 34 years. He became chief of the factory design bureau at his new location. In 1941, UZTM received a number of initiatives from Sverdlovsk that had been discussed in the GAU. For example, a project for a 107 mm antitank gun under the designation UML-20 was discussed in July. Like the M75, this gun was based on the ML-20’s carriage. But as with a number of other similar projects, the UML-20 did not go beyond the conceptual design stage.
Despite the design bureau’s competent team, the new task was a serious challenge for the factory. In a letter to GAU Deputy Chief Gen. V. I. Khokhlov on October 7, 1941, UZTM Chief Engineer A. S. Ryzhkov said the following: