There is a Vietnam-era helicopter pilot who has a souvenir helmet with a 12.7mm hole in either side of it, which is why I don’t trust any pussy .50BMG and carry a 14.5mm DShK.
The cranial vault is tougher than most people think.
Handguns are a lot less powerful than most people think. (Yes, even the “mighty” .45)
Ball ammunition is a lousy stopper and often deflects from skulls and ribs.
Pistols are a poor choice to shoot a body with. I don't have faith in any of them, not even .44 Magnums. The only reason you'd ever use a pistol for self defense is because you'd look silly wandering through the produce department at the grocery store with a slung Garand or pushing your stroller while carrying an M4 carbine.