RE: biggest American critter taken w/30-30?
I'm not sure if anyone can answer that. But I know that I think it was 2003, here in PA, the heaviest black bear ever taken in PA, 824 lb, was taken with one shot from a 30-30.
I'm sure there have been a few moose and bison taken as well. And these critters can weigh up to 1800 lb.