I've never shot one upside down or sideways but will try it next trip to the range. I have limp wristed them beyond reason and never a bobble. I had some American Eagle, Fiocchi, White box and Remington fmj along with some low power reloads and everything ran fine. I was hitting the steel consistently with a miss here and there while standing, no doubt my fault as I was just plinking for fun, something I do more and more. But again I was just happy to get to shoot, have had a bad cold and sore throat for a week and was off work for the day. Bench resting was not on the list, just plain ole plinking, and of course, 100% reliability.
I never pass up those old P guns and keep an eye out all the time. For a gun that suffers some bad press, they are quite popular, easy to trade, and sell. Good luck on your searches.