I report on the results of the proving grounds trials of the experimental SPG that uses a 76 mm tank gun mod. 1940 (F-34) on the chassis of a captured German medium tank PzIII (or StuG) produced by factory #37 according to the GOKO decree issued on January 19th, 1943, #2758ss.
Trials were held at the Sofrino proving grounds from March 13th to March 20th of this year in the amount of 434 shots and 280 kilometers, supervised by the commission led by Lieutenant-General of Artillery, comrade Tikhonov.
The prototype supplied for trials satisfies tactical-technical requirements.
The major characteristics of the 76 mm SU-76 SPG are as follows:
- Front: 45 mm at 45 degrees
- Side: 25 mm at 20 degrees
- Rear: 25 mm at 20 degrees
- Roof: 10 mm
- Ammunition capacity: 95 shells
- Vertical gun angles: -5 to +15 degrees
- Horizontal gun angles: +/- 10 degrees
- Height of the fighting compartment: 1760 mm
- Bore axis height: 1870 mm
- Crew: 4
The design of the SPG is very good. The stability when firing is good. The SPG is easy to service. The accuracy is satisfactory. The performance of the vehicle matches that of the PzIII, recorded in the service manual of the latter, and are characterized by insufficient traction of tracks with a slippery frozen road, which results in drifting and slipping. The reliability of rubber tires and drive sprocket is insufficient. This deficiency requires the speed to be limited at 25 kph. When moving on icy or frozen terrain, it is necessary to install V-shaped German spurs. The commission decrees that the SU-76 SPG is adequate for tasks delegated to this type of self propelled artillery, has passed trials, can be recommended for adoption by the Red Army, and must be produced immediately, provided that satisfactory tires can be found or produced domestically, spurs, spare road wheels and sprockets, and careful quality control and re-checking of all PzIII and StuG tanks used in production.
I consider the tested SU-76 76 mm SPG to be ready for adoption by the artillery branch and mass production.
GAU KA Chief, Colonel-General of Artillery, Yakovlev"
Note that the SU-76I weighed only 22.5 tons, compared to 22 tons of a mid-production StuG or 20 tons of a late production PzIII, so excess weight can't be blamed for this fragility of the suspension.