The IS / KV-1S 122mm sniping
can be pulled off, regularly. I've done many of that. Thing is, you need a good crew to pull it off consistently. The KV-1s has that advantage because it requires a crew of 5 as opposed to the IS' 4. With the initial 100%, BIA and other skills, you will find your crews to be very proficient in long-range combat with the mighty 122mm.
I suppose that is the reason why I eventually settled with the Soviet heavy line, after learning what crews can do with German tanks. Crew skills drastically minimize the default hardware deficiencies of any vehicle.
Just ask Wil what I've done with my IS-3 once from across the map
- Tak