Claims almost always were overstated. In air-to-air combat, during Korean War, F-86 Sabre was believed to have had 10:1 exchange ratio against MiG-15. Turns out, it was closer to 2:1. I suspect that claims against tanks were no different. IIRC, in A-10 tests, it had turned out that pilot would believe tank destroyed due to apparent damage done by cannon... but all of that would be dirt thrown up around the tank, or shells exploding against armor. Which again means that any claims will have been overstated.