A Comm for Historymemes

My very armchair general-ish educated guess:

If they have an HE round loaded, a shot might damage or activate the shell's very sensitive front facing fuse, causing it to immediately explode and also cause any other readied shells near the loader to explode, virtually guaranteeing the tank crew's death.

Other shell types, they have thick and inert ballistic cap that is propelled with enough velocity to shred armor. Basically an oversized bullet themselves. A pistol round would not go through the ballistic cap, only crumple and deform it. But there may be a chance it would make the shell misfire and damage the barrel when the tank crew attempts to fire.