Finally found one nice article i read time ago.
In august 41 near Leningrad city soviet heavy tank KV-1 under 1st lieutenant Kolobanov command ambushed german tank column and destroyed 22 (twenty two) tanks and 2 anti-tank guns. His KV-1 had additional armor plates increases his armor up to 100mm and was almost completely immune to german tanks fire. After end of fight crew counted about 130-160 dents on armor, all rounds bounced off. Most significant damage was wedged turret after hit in turret-hull joint (weak spot of KV-1).