After the launch of SU-152 mass production the design was slightly modified to improve reliability. Initially the SU-152 lacked a machine gun, which was recognized as a severe weakness in urban warfare and other close combat. To solve this problem the DShK 12.7 mm anti-aircraft gun installation was developed in the summer of 1943. Some SU-152s received it after repair. The SU-152 was the last member of the KV family of tanks in mass production, and was replaced by the ISU-152 on the ChKZ production lines in December 1943. The exact number of SU-152s produced differs even in Russian sources, with the most common figures being 670 or 704. The SU-152s that survived World War II were withdrawn from Soviet Army service in 1954.