Actually it was just partially correct. You tell sniper by 3 things:
1. Both rails and notch are present
2. It is a Tula 1941 or 1942.
3. Serial number prefix is present on Ratnik list.
Otherwise you can get yourself fake. And they are out there, I see them more and more often. We have ppl that want to convert regular rifles to snipers by filing the notch and we have dealers doing that (at least some of them honestly admit those are repro snipers, but will next owner admit it during the next sale?). Btw there are even faked "field snipers". Wait until SVTs go in price , we will see even more.