With that said, I would love for someone to 'volunteer' to be shot in the chest at 5-7 yards with a .22 pistol. Damn right no one is going to volunteer, because we all know a well placed shot can kill you, be it a .22 or .45.
It's not about "volunteering" to be shot; we all know that's a dangerous chance.
But, when your life is on the line and a BG is determined to hurt/kill you, is it enough to STOP them? There's a reason hunters don't use a .22 rifle for hunting big game; they know it CAN do the job, but it doesn't do it as reliably as a larger, more powerful cartridge.
If the .22 LR was a great stopper of men, the military would have used it at some point. Imagine soldiers being able to carry a few thousand rounds of effective ammo with them that easily.
The truth is, while it CAN kill a person, and is certainly dangerous, it's not a great stopper of a determined agressor. No military, law enforcement, or any other combat type group uses it as standard issue anywhere in the world, and there's a reason for it.
If it's what a person shoots well, and they're unable to effectively handle something larger, then it can certainly be an effective deterrant to crime under many conditions. If a person can handle more, and is able to shoot a bigger gun well, then there's a better chance of them being effective with their firearm if they're ever forced to use it.
three things can contribute to stopping a criminal quickly. A CNS (Central Nervous System I.E. brain, spine) hit will stop them right now, and the threat will end very quickly, no matter the caliber or cartridge. Another is a loss of blood pressure. A bigger hole bleeds more, and a bigger bullet damages more internally and causes more blood loss. The third is a major support bone (hip, leg) being broken, and a larger bullet does that better, too.
Anything else may kill in time, but might also leave an agressor alive and able to hurt or kill you.
It really is that simple.
Daryl