That is an interesting penetration test you did with the phone books and applicances.
The .22 outperformed the cap and ball, big time.
I have done penetration tests on boards. With my .44 Colt and 30 grains fffg, I go through a 2 inch pine board easily. The bullet dents, but will not stick in the 1 inch pine board behind that.
The balls get deformed a little in these tests.
That round ball has a lot more energy than the .22, but it has so much more surface area it will not penetrate as well.
Combat usage shows that the cap and ball pistols are well proven mankillers.
Still, it wouldn't take much of a bulletproof vest to stop these round balls.
Think I will try some cloth penetration tests, to see how thick of a coat it would take to stop the ball.