But in terms of humans, most hand gun ammo would be the same and you need to move up to things like shotguns if you want any truly measurable difference in the margin, IMO.
Now think for a bit...
Are there any law enforcement agencies that you are aware of that issue a .22 caliber handgun as their sidearm?
Are there any militaries, anywhere in the world, that arm their troops with either a .22 l.r. sidearm, rifle or carbine?
Why do you suppose this is?
Now, if the poster truly believes that caliber in handguns makes no difference well why not the .22 short or an airgun?
"Most handgun ammo would be the same..."
Nope. When folks argue that, in terms of effect, there may be little difference in handgun calibers they are usually speaking of standard service calibers and leaving the .22 l.r., the .25 acp and the 32 out of the discussion.
.22 rimfire ammo is more likely to misfire than centerfire.
.22 ammo does not penetrate as deeply as defensive calber handgun rounds.
.22 ammo does not strike with as much force as defensive caliber rounds.
.22 ammo is more likely to glance off bone.
.22 ammo is less destructive of tissue and delivers less shock effect than centerfire rounds.
Folks can argue that with it's low recoil the .22 allows for better shot placement. Some truth to that but gunfights are funny things. Remember the last time you were in a fist fight. Each blow you threw you wanted it to be a stunner. You wanted to knock the fella out. Bust his nose! Hit him a solid one to the jaw! But...most blows you threw missed the critical areas sometimes by a little but and sometimes by a bunch. Now that was at arms length away.
So if you miss the critical area by a few inches, which is likely and very common, the "three to the head" becomes one to the collarbone, you want that to be with a pebble or a brick? And when you do land that solid hit you want it to be with a 4" Philips screw driver or a Bowie knife?
tipoc