Well, the M61 was only able to penetrate about 90mm of RHA in reality.
The Italian 75mm AP round doesn’t even have 75mm of armor from the tip to the cavity.
Thus it will easily break appart when stricking anything above caliber thickness.
Probably even easier when it’s sloped armor.
Yeah, but that’s just the result of the penetration calculator.
I’m pretty sure that the Italian APHE would be a lot worse under realistic circumstances.