| The ISU-152 (in Russian ???-152) used the same concept as the earlier SU-152: a large gun-howitzer mounted in the hull of a heavy tank. The ISU-152 used the same gun as the SU-152 but on the hull of an IS-2 tank instead of the KV-1. Development began in June 1943 in the Design Bureau of Experimental Factory No. 100 in Chelyabinsk. At that time it had became clear that the KV-1S heavy tank would be replaced by a new heavy tank design, the Iosef Stalin (IS). The combat performance of the SU-152 self-propelled gun, based on the KV-1S, prompted Soviet engineers to investigate the production of a mobile gun using the new tank as a base. The design work was conducted under the supervision of Joseph Yakovlevich Kotin, the chief designer of Soviet heavy tanks. The main designer for the ISU-152 was G.N. Moskvin. During early design work, the project was designated IS-152. In October 1943 the first prototype, 'Object 241', was built. It successfully passed plant and state testing. The vehicle, now named ISU-152, started mass production at the Chelyabinsk Kirov Factory (Chelyabinskiy Kirovskiy Zavod, ChKZ) in November 1943. In the following month the ISU-152 completely replaced its predecessor the SU-152 on ChKZ production lines. | 
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