After unsuccessful firing tests of SPG KV-6, it was decided to place the installation of 2 x 76 mm cannons in its fighting compartment. The new version of the SPG was tested in 1942. The tests were successful, however, in connection with appearance of new SPGs in the Red Army, weapons power of KV-7 was considered as insufficient. Further testing and modernization of SPG KV-7 were carried out.