AP Penetration Calculator & Weapon Guide

[low_bidder]

Her are some real world tables based on firing range numbers;
http://www.geocities.com/phsacre/WW2pen.html

Some guy named Byrd ( or Bird, maybe) wrote a massive book on the topic. He found that with the larger caliber weapons, sometimes they wouldn't penetrate, they would just knock that bit of tank into the interior of the tank.
The former tank crew prolly wasn't concerned about the difference.