Originally posted by John Hynds
I have seen what 75 and 76 mm ap rounds do to Shermans not pretty. There was a reason the crews called them ronsons(a lighter during WWII era). Get hit by anything and they go up in fireballs.
Early Shermans had a propensity to catch fire due to inadequate ammunition storage, a situation that was largely rectified by the time of the Normandy invasion. After that point they were no more likely to catch fire than any German tank.
The German 75mm guns were much more powerful than the US 75mms. I am not sure where you have "seen what 75 ap rounds do to Shermans," but if you are referring to pics of battlefield damage, you are comparing apples to oranges.
Look up the thickness of the armor of the T-34/76, earlier PzkwIVs and the Sherman. You will see that the Sherman is comparable. But be cautious with the listed armor of the PzkwIV(H) and later IVs. Usually the armor listed includes the "skirting", which was added to defeat shape-charged weapons and did little to stop AP rounds.