http://www.imfdb.org/wiki/Sniper_%281931%29
Some stills from the film. Looks like the Soviets had some sort of setup similar to the Austrian M95 system with a single rear "leg" and windage in the front base. I don't recognize the scope off hand, possibly an early Voigtlander or but maybe one of the Soviet's first efforts? Or something they captured from the Austrians in bulk?
The film looks interesting; they seem to have enough kit for a highland company; I wonder where they got that?
The Ross was probably a good choice for sniper training, which was later encouraged heavily through the OSOAVIAKhIM: accurate, quick handling, in limited supply and using a non-standard ammunition.
Somewhere in their museums and archives must be some interesting documentation on all this.
Incidentally, the Russians have been putting online large amounts of captured Germandocumentation in the last few years. For those who can read German it is a gold mine.