It should be noted that the use of the T-9 sight from the KV-2 was a temporary solution. The system assembled for installation on the KV-14 prototype was equipped with a T-10 sight with scales inscribed for the ML-20’s ballistics. However, time was needed to begin manufacturing the T-10, so the first KV-14’s were equipped with a T-9, which were readily available after production of the KV-2 ended.
The system underwent factory testing at Factory No. 172’s test range on January 21. In all, 58 rounds were fired, 5 with reduced charge, 3 with a full charge, and 50 with supercharge. The system functioned without a hitch during testing; the shift in elevation during firing was two thousandths of a degree. No warping was found after the proof tests, and the effort required to operate the flywheels was within normal limits.
Assembly of the KV-14 prototype was essentially finished by the morning of January 23. The only delay was due to the gun system, which arrived that evening. Mounting of the gun took all night, and the work of assembly ended the next day, earlier than expected. As expected, when assembly was complete, the KV-14 with serial number 3011 was sent off for factory tests, which concluded on January 29. Exactly a year had passed since Ginsberg signed the operational requirement to mount a 152 mm howitzer in a KV-7.
In developing the KV-14, the SKB-2 team took maximum advantage of its experience in building the KV-7. The height of the superstructure remained unchanged, but the interior space was increased by moving the front plate much further forward as compared to the KV-7. As on the KV-7, a special skirt was added to the lower part of the mantlet to prevent the system from jamming on the upper front plate of the hull. For improved ballistic protection, the side plates of the superstructure were angled in both the vertical and the horizontal planes. On the one hand, this solution increased the probability of a ricochet, but on the other, it cut into the interior space. In accordance with the requirement, submachine gun ports were installed in the superstructure’s front and rear plates, and a double hatch was installed in the rear for loading ammunition and for crew access to the fighting compartment. In addition to the rear hatch, there were hatches in the superstructure roof for entry by the loader and commander (the commander’s hatch had a signal port). In addition, a PTK panoramic sight was mounted in front of the commander’s hatch. Vision blocks with mirrors similar to those used in the KV-1’s turret were installed to improve visibility around the superstructure. Four vision blocks were originally planned, but a vision block for observation to the right was added to the prototype and the production vehicles and was used by the breechblock operator. For a variety of reasons some of the vision blocks were located relatively far from the edge of the superstructure roof, creating large blind zones around the vehicle.
In developing the new SP gun, its creators had to deviate somewhat from the operational requirement. According to specifications, the KV-14 crew was supposed to consist of six men, but the fighting compartment had no room for the radio operator. That problem was solved by combining the functions of the commander and radio operator. The 9-R radio was placed in front of the commander’s position. In addition, the size of the fighting compartment prevented use of the standard fuel tanks from the KV-1. Instead, fuel tanks with a total capacity of 480 liters were placed along the sides of the superstructure. That location greatly increased the risk that they would be struck by enemy shells, but with such a compact layout, there was no other place to locate the fuel tanks. Some deviations from the Kirov Factory design bureau’s initial design were also required. The GABTU required that tanks and SP guns be equipped with handrails for riders to hold onto. Handrails were not originally part of the KV-14 design, but the prototype had them.
The strict specifications regarding the fighting compartment’s interior dimensions meant the designers had a hard time finding a place to put the ammunition. The main ammunition storage rack was located on the left side of the superstructure, and some of the rounds were located under the gun. With this arrangement, getting at the second group of shells proved challenging, but there was no other place to put 20 rounds. On the other hand, the fighting compartment was relatively spacious. Considering that the average height of a tanker was 160–170 cm, the crew could stand inside the KV-14 without bending. The overall height of the vehicle was 2450 mm; in other words, it was on a level with the T-34 and 20 cm lower than the KV-1S. In addition, to ease movement of crewmembers within the fighting compartment, the commander, loader, and breechblock operator had folding seats.
All things considered, the Chelyabinsk vehicle was unique. No other army had a weapon system with its combination of relative compactness, good armor protection, and powerful weaponry. Instead of the narrowly specialized machine for attacking fortifications that the artillerymen wanted, they got a general-purpose assault SP gun that went down in history as the “Beast Killer.” However, the KV-14 would not acquire its reputation as the scourge of German armor until the summer of 1943; first, it had to undergo proving-ground tests, which were scheduled for early February.
According to the test program, the KV-14 was to traverse a difficult 200 km route, and plans called for the ML-20 to fire 296 rounds. The testing took place at the Chebarkul Test Range. In fact, the route from Chelyabinsk to the test range and back constituted the road test. It did not travel 200 km, however, because the distance to the test range was 85 km, and it traveled 88 km on the road back.
The trip to the test range took place under very harsh conditions. Not only was the highway covered with snow, the outside temperature was -42°C. On top of that, there was water in the fuel, which caused the engine to stall frequently. As a result, it took the KV-14 13 hours to cover the 85 kilometers.
The firing program was cut short: instead of 296 rounds, 234 were fired, of which 100 were supercharges. The firing for durability revealed no warping in the gun or the mounting parts.
An average of 2.8 rounds per minute was achieved during the rate-of-fire test using the first row of the storage rack. This was below the specified rate, but it was not bad for such a high-caliber gun. Firing was carried out with the hatches closed and the engine running. Depending on the rack used, reloading took from 16 to 30 seconds. The SP gun recoiled 70 to 250 mm during firing, and the stern or bow dropped 10–80 mm. The test program also included firing from short halts. A series of firing from halts at ranges of 800, 600, 400, and 200 m was carried out. Five rounds were fired after each halt. Firing accuracy was acceptable, especially for an SP gun intended for engaging enemy fortifications. It should also be considered that the vehicle was a prototype, and not all of the bugs had been worked out of its individual assemblies by that point in time.