Being classified as a medium still doesn't make it any good. If your tank can be pierced by machine guns then you seriously need to rethink your designs. Hell even the 30-06 can penetrate the side armor at 100 meters and the rear from 200 provided they're firing M2 ap rounds. Even if they aren't there's enough 50 cal M2 machine guns around that they could just light it up with one of those. It can pierce the armor on the front from a little under 500 meters and the side and rear from even 1000 meters.

Poor Maus, to have to suffer such indignity.