June 9th, 1935
The 203 mm mod. 1931 howitzer on the self propelled chassis SU-14 was twice delivered for trials to NIAP. First time, from August 1st to August 15th, 1934, for gunnery trials in the presence of the People's Commissar of Defense, comrade Voroshilov. Second time, from April 14th to April 27th, 1935, for factory trials.
It was not possible to test mobility, maneuverability, and agility of fire, as the suspension was broken both times when the SPG arrived at the proving grounds. Between August 1st and August 15th, 1934, and April 14th to April 27th, 1935, the SU-14 fired the following shells:
- 203 mm howitzer, barrel #77
- Reduced power shells: 6
- Regular shells: 9
- Increased power shells: 5
- Total: 20
From these trials, conclusions can be made:
- The 203 mm howitzer mod. 1931 on the self propelled chassis SU-14 is unstable at angles of even 45 and 60 degrees when tracks brakes are on, but trails are not deployed.
- When track brakes are off but trails are deployed, the SU-14 is stable at angles of 20 degrees, 45 degrees, and 60 degrees, and mostly stable at 10 degrees (vehicle shifts 90-100 mm).
Many defects were found specifically in the artillery system and overall, and trials were stopped. The vehicle was returned to the factory."