Shooting in the face where there isn’t cloth won’t necessarily help - if the hat just stop bullets aimed for the head (like a magical forcefield) then it’s pointless.

Also, it’s not gonna hurt like hell and bruise the shit out of them - you’re citing Newtonian mechanics when it’s fucking magic. Hell, maybe the forcefield just deletes the bullet instead of deflecting or blocking it.

“Shoot at it until it dies” is great advice generally, but if you shoot a water pistol at a fish then you’ll be there til you run out of ammo.