The first solution to this problem was quite original. Despite his initial dislike of the KV-1's two guns, Stalin gave the order for a three-gun mount.
"By personal order of People's Commissar of Defense Comrade Stalin, Kirov factory (in Chelyabinsk ChTZ) is developing triple gun mount (two 45 mm tank guns and one 76 mm F-34). For development of these SPGs, Kirov factory needs four 45 mm guns urgently. In order to mass produce a KV with three guns, it is necessary to supply the Kirov factory with 180 such guns in December of 1941, and 260 in January of 1942, without recoil mechanisms, semi-automatic mechanisms, or sights." - CAMD RF 81-12104-79
Two guns made the KV's turret crowded enough, so the turret had to go. The result resembled the ultimate conclusion of that project, the SU-152. A front fighting compartment on the KV-1 hull, with up to 100 mm of front armour, fully enclosed from all sides. The armament is where the construction differed radically. Instead of the commonly seen one gun, the new SPG (indexed KV-7) had multiple. Different versions had 2 45 mm model 1932/34 guns and 1 76 mm F-34 gun (U-13), and 2 76 mm guns (U-14). Regardless of the configuration, the guns shared a mantlet, and aiming mechanisms. The guns could either fire independently, or all at once. The three gun variant stored 93 shells for the 76 mm gun and 200 45 mm shells. The two 76 mm gun variant had 150 shells.
At this point, Stalin seems to change his mind. "Why have three guns? Put one in, but a good one!" However, his opinion of the developments was not entirely negative, as he promoted Kotin from colonel to general on that same day.
The KV-7 comes up in a phone conversation between Zaltsmann and Stalin on January 24th, 1942.
More solid criticisms were compiled by assistant of the head of the 4th division, 3rd department of GABTU, Major Gorohov.
- It is helpless when fighting tanks. The angle of fire is only 15 degrees to each side.
- It cannot be used to combat concrete bunkers, as the caliber is too small.
- I think it is more reasonable to install a large caliber gun, approximately 152 mm, like the M-10 gun on the KV-2."
However, before the ZIK-20's demise, it was equipped with an even more optimistic artillery system: a Br-2 152.4 mm gun.
Another attempt at a 203 mm gun was undertaken at Perm in 1943, indexed SU-203. A "SU-14 type" SPG was equipped with a 203 M-4 mortar, based on the B-4 howitzer. The ammunition used by the two was the same. 20 100 kg shells were stored inside the tank.