Here we go again. Because of the fabled capability of wild/feral hogs they can only be killed with a silver bullet fired from a .50 cal or larger crew served weapon. Not true. Hogs are, at best, just slightly harder to kill than deer. They're not bullet proof, bullets don't bounce off regardless of the caliber. Like most other wild animals they would rather flee than attack, unless wounded and /or cornered, or protecting shoats. Even when a wild/feral sow has little ones she’s more likely to run than fight.
As an addendum here, a domestic sow in a pen with shoats may try to eat you up if you mess with her brood, but then she’s lost her fear of humans. Plus, has nowhere to run.
Will a 9MM kill a hog? Yeah, deader than a rock, providing that the hog is hit in a vital spot at a reasonable distance. Not only will a 9MM kill a hog, anything from a .22 to a 12 gauge will too. How do I know? In 70 odd years I’ve killed more than a few wild/feral hogs. You just have to shoot ‘em in the right spot.
Here's a picture of one taken last year with a 9MM pistol. Head shot.