IMO, most folks hit by a 9mm, or any caliber, are going to
have an immediate priorities change, as in: "Aw crap, time to
head to the hospital!"
Not that you can depend on that, but in 50+ years of life,
luckily, to date I haven't found a need to mortally wound
another person ever, with anything. So if I haven't
killed anyone with a 2x4, hammer or tire iron by now, it's
unlikely I'll have to do so with a gun.
Soo, actually, the way I see it, a .22 will do, also.