After the conclusion of the Great Patriotic War, People's Commissar of Tank Production Malyshev ordered each factory to write up a record of their activity during the war. This is what UZTM wrote about their attempt to convert the strange looking KV-7 into a functional SPG.
"U-18
This is a project of a KV-7 SPG with the powerful 152 mm ML-20 gun.
The gun is also installed using a frame mount. The aiming angles are +15 to -5 vertically, 7 degrees 30 minutes to each side horizontally, or 15 degrees in total. The gun has good ballistic performance (43-51 kg shells, 550-650 m/s muzzle velocity) which gives 98 mm of penetration from 1000 meters compared to 49 mm from the ZIS-5 gun.
The explosive charge of the 152 mm shell is three times greater than that of the 76 mm shell.
Design work was done by comrade G.N. Rybin, comrade K.N. Ilyin, and others.The U-18 project was presented by the factory and approved by the People's Commissar of Tank Production and Main Auto-Armour Directorate and was transferred to the Kirov factory for use during the development of the SU-152 SPG.
During the Patriotic War the 152 mm caliber of the SU-152 was the greatest among all domestic and enemy tanks and SPGs."
However, the GABTU had a different opinion about what happened to the project.
"To the chief engineer of the Uralmash factory, comrade Umnyagin
September 24th, 1942
I reply to your letter #3655/48s written on September 4th, 1942 regarding the SPG project U-18. An analogous project proposed by comrade Petrov was already discussed between September 12th and 14th of 1942.
Chief of the 6th Department of the GABTU BTU, Engineer Lieutenant Colonel Kovalev"
CAMD RF 38-11355-937 p.124
CAMD RF 38-11355-937 p.124