I've been reading debates like this on various forums for years.
I haven't seen it lately, but for a long time many of the self proclaimed "experts" swore that anything less than a 9mm was completely worthless and only a fool would carry one. Yet, these same "experts" also recommended 2" J-frames.
OTOH you had those saying carry the smallest gun because you will actually have it with you rather than a big one left at home.
The debate goes on and on.
I'm no ballistics expert nor have I been a cop, medical examiner or whatever. I do know that .22s have killed people and other folks have survived multiple hits with .44 Magnums. The fact is, you just never know how a person will react to being shot.
At various times I've carried just about everything from a .45 Colt to .25 auto. I've never felt undergunned with any of them. You just need to know the strengths and weaknesses of what you have and make the best use of it.
Got a 9mm or .45? You're all set for an extended firefight out to 25 yards or more. But how often does that really happen?
What's that old saw? 3 shots at 3 feet in 3 seconds or whatever? Most self defense shootings happen real fast and real close. Or at least that's what the so-called "experts" claim.
All you have is a .22? Fine. Odds are you're gonna be a bad breath distance anyway. Stick the gun in his damned face and fire.... several times! That should take care of the problem.
JMHO, but I don't think its what you carry so much as what you can do with it.
Just for the record, I happen to be a fan of the Walther PP series pistols and have carried them. In fact, I carry a Colt Mustang XSP on my daily exercise walk. Yep, just a little bitty .380 and I'm perfectly fine with that.
FMJ vs HPs? Why does it have to be one or the other? My magazines are loaded to fire 2 federal Hydra-Shoks followed by four Winchester FMJ flat points. If I have to use it, I'm gonna empty the magazine. I'm sure one or the other will get the job done.
BTW: I carry a spare mag too.
Anyway, y'all can get back to arguing statistics and who saw what. These are just the opinions of one old guy.
But then, I'm no "expert" either.