Contains range/penetration graphs for all tanks and at guns.
Link originally posted on official game forum (http://www.digitalmindsoft.eu/forums/viewtopic.php?f=149&t=10042).
http://www.militis.pl/bd/penetration.pdf
Complete guide to tanks with nice comprehensive images created by Cat
You can find it on his blog.
http://baserespawn.blogspot.cz/2011/07/mowas-tank-combat-guide.html