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.