It's based on the table about 1/4 of the way down this page under the heading "Penetration Table 02: Sherman A2, Sherman A4."http://www.fprado.com/armorsite/tiger1.htmKeep in mind thickness is not the only factor in armor penetration.
Well depending on the range, thats not unheard of. I shot a T-34 with a panzer at 3200yds with little effect untill I got a lucky kill on the driver (I assume). And the M4 has the same frontal armor as a T-34.
3200 yards is almost 2 miles away nemesis...you cant even see an enemy tank that far out let alone hit it unless by sheer luck you can aim a shot that far you probably wouldnt even see the shot land
3200 yards is the bottom tick on the tank sight. If you can't see a tank at that range in Aces High, there's something wrong. I've seen one of my buddies sit in a Panzer and kill things at over 5k yards.