[HolyGrail]

Ball turret movement should be managed by hydraulics and since the turret ball could get stuck in such position that you can't open the hatch or too late to bail out or belly landing you sure would get crushed to death .
Throw in wounded or some already dead crew that can't help you out and pilot about to belly land and you can get an idea.
I believe it does happened , not every day of course but there were such incidents .