You can throw energy tables out the window when talking about a lead round ball, they are terrible on paper...
One other thing...Because of that large frontal area the faster you push them the faster the slow down...Wrap your brain around that one...So adding more powder isn't the answer to gain energy...With the round ball increasing the bore diameter is the answer to adding more energy...
Finally....Everything you hear about too much powder behind PowerBelts also goes with roundballs...You can actually upset it so fast and flatten it out so that you get less penetration with more powder...