When the firing trials were complete, the KV-14 was driven back to Chelyabinsk. At -16°C, the outside temperature was quite reasonable for early January. As before, the highway was snow-covered, which increased fuel consumption to 4 kg per kilometer. Nevertheless, the vehicle covered the 88 km return route much more quickly—in 6.8 hours. It reached an operating speed of 13 km/h and a cruising speed of 20 km/h. There were no failures in the engine or transmission during either trip. The mechanism securing the gun in travel position worked properly. No special tests were performed during the trip to the test range and back because the SP gun’s chassis was the same as that of the KV-1S. In all, the entire test cycle took five days—from the 1st through the 5th of February, 1943.
A commission headed by GAU Artillery Committee chief V. I. Khokhlov (who at that time held the rank of lieutenant general) drew the following conclusions on the basis of the test results:
The 152 mm self-propelled gun prototype presented for testing satisfies the operational requirement except for rate of fire, during which the maximum value achieved was 2.8 rounds per minute in the third series of 10 shots using shells and cases from the nearest storage rack with the gun in optimum position, compared to 3–4 rounds per minute as required by the operational requirement.
We concur with reducing the crew size to four men since external communications by radio can be assigned to the gun commander.
The accuracy of fire by the self-propelled gun obtained both as a result of its special definition and during firing from short halts per the rate-of-fire requirement was completely satisfactory.
The gun mounting parts, all of its mechanisms, and the vehicle’s hull and assemblies are durable during both firing and during travel. Inspection of the marked assemblies revealed no warping.
The self-propelled gun’s stability during firing is satisfactory: the backward movement is reversible in the overwhelming majority of cases, and no separation of the tracks from the ground was observed.
Misalignment of aim was insignificant, and was no more than two mils in the horizontal plane on the aiming circle. There was no misalignment in the sight settings.
The ride characteristics of the self-propelled gun were the same as for the KV-1S tank’s running gear.
Servicing of the gun, both during preparation for firing and during firing, was satisfactory.
The vehicle and gun assemblies are accessible, both during preventive maintenance and during halts while on the road.
The sights are in convenient locations.
The 152 mm self-propelled gun is well-designed. The spacious roof of the fighting compartment and the armor design make it possible to assemble the gun and the vehicle separately and install the fully assembled gun in the vehicle together with all of its components. The gun is well balanced: little effort is required to operate the laying mechanism flywheels.
The gun opening in the firing compartment is well protected at all elevation and traverse angles. The illumination in the fighting compartment and the driver’s compartment is completely satisfactory. The gun commander is provided with vision devices and both internal and external communications equipment. The SPT&A kits for both the gun and the vehicle have been developed, and the prototype equipped with a vehicle-transportable kit.
Loading ammunition into the vehicle through the hatch is convenient.
VI. Design flaws
A. Items requiring correction for the first production run
The firing and road tests revealed a need to make the following design modifications to the self-propelled gun:
1. Prevent cases from catching on the breech face when they are inserted into the bore from the loading tray.
2. Make it easier to remove ammunition stacked on the upper shelves.
3. Mount a sight in front of the driver for coarse aiming of the vehicle at targets.
4. Install a Luch-type device for illuminating the gun sight.
5. Move the traversing mechanism mount that interferes with the driver.
6. Include a manual screw-type ejector in the gun’s SPT&A kit (1 ea.) for extracting swollen cases without exiting the vehicle.
7. Add a step to facilitate entering and exiting the fighting compartment.
8. Install a barrier to protect the oil tank fittings from being damaged when removing shells from a shelf.
9. Relocate items in the artillery SPT&A kit (panoramic sight, ejectors, fuze wrenches, rammer, etc.) to place them close at hand for the crew members that need to use them in combat.
B. Items requiring additional design work
1. Better facilitate servicing of the gun during combat and increase the rate of fire. To achieve this, the Commission recommends the following approaches:
a) Extend the rear turret plates to match the maximum size of the front plates.
b) Attach the storage rack for all shells to the left rear side turret plate by lengthening the rear plates to match the front.
c) Attach the storage rack for the cases on the right side of the fighting compartment to enable assignment of the loading of cases to the breechblock operator.
d) Design the gun to have a sliding wedge breechblock.
e) Relocate the fuel and oil tanks inside the fighting compartment as a result of the change in the turret size and ammunition location.
Alter the tank sizes, abandoning the use of production items.
2. Move the traversing mechanism housing to the right in order to improve working conditions for the driver.
3. Replace the steering clutches with a planetary steering mechanism.
4. When manufacturing the KV-1S tank’s hull and turret of highhardness armor and replacing its mirrored vision blocks with the MK-4 or T-80, make the appropriate changes in the self-propelled gun drawings, as well.
5. Make all changes to the self-propelled gun drawings needed for manufacture and testing of the first self-propelled gun production run.
VII. Conclusion
1. The self-propelled gun mounting the 152 mm gun-howitzer model 1937 on a KV-1S chassis developed by designers at the Kirov Factory of the People’s Commissariat of the Tank Industry and Factories No. 172 and 9 of the People’s Commissariat of Arms, with its artillery system manufactured at Molotov Factory No. 172 and its chassis manufactured at the Kirov Factory under the People’s Commissariat of the Tank Industry, has met the requirements for this type of self-propelled artillery and has passed proving-ground tests.
2. It is hereby recommended that this self-propelled gun be placed in service with Red Army artillery and that mass production of the system begin with changes made in accordance with paragraph A of section VI of this report.
3. It is hereby recommended that the Kirov Factory of the People’s Commissariat of the Tank Industry and Factories No. 172 and 9 of the People’s Commissariat of Arms develop a draft self-propelled gun project with the changes stipulated in paragraph B of section VI of this report and present it to the Artillery Committee for review by March 15 of this year.{5}
