Good post John. Allow me to throw in another variable. Given that in an attack launched at close range, all of your motor skills go to hell and you can't hit that eye socket with your 22. Maybe you're just shooting at form without aiming due to the proximity of the threat. Now. which caliber do you want? As for me, I'll wanta make a lot of big holes fast!
I'm not saying carry a .22 to the exclusion of everything else. I'm saying that, even in your scenario it most likely still doesn't matter. If you are in a situation where your opponent has closed to within contact range of you before you were aware of him, then you have screwed up tactically (or are just plain unlucky). Hoping to save your bacon with a magic bullet is just that... hope.
There are four factors (not including luck, good or bad, probably the primary factor, but having the four factors below down pat will increase your luck) that will decide whether or not you survive a deadly assault, in decreasing order of importance:
Situational Awareness
If you are oblivious to your surroundings, just walking around with your head in the clouds, then if someone wants you they're going to get you. If you have your head in the game and spot something hinky, then you can often avoid trouble. Don't go into the convenience store if you can see the clerk holding up his hand through the window. Don't walk down that dark alley if you can see shadowy figures peering out from behind the dumpster (don't go down it anyway).
Proper Tactics
Let's say that you find yourself in a threatening situation. Perhaps you are in a parking garage and a street bum pops up a row over with a piece of rebar in hand asking for your wallet. Put a car between you and him as quickly as possible, back away, and keep putting more cars between you and him (while keeping your head up and checking your six for his scummy partners). Tactics can save your life without having to display or use a weapon. Seeking cover at the first sign of trouble is a good tactic, and so is running away if it can be done safely. Another good tactic is not letting the person threatening you with deadly force know you're armed (with a gun, knife, briefcase, etc.) until you have used that weapon with surprise and accuracy in a sneaky counterattack.
Skill With The Weapon(s) at Hand
Regardless of the weapon you have, if you can't employ it effectively then you might as well not have it. What good is the finest 1911 if you can't hit a barn from inside? A street punk with rudimentary martial arts skills will close with you, take your empty gun away, and pistol-whip you with it. If push comes to shove, you need to know how to shove and be able to perform under pressure.
Choice of Weapon
Now we're down to the least important rung on the Survival Ladder. If you have the other three attributes, then regardless of your weapon you will be able to employ it with maximum efficiency, surprising your opponent, and dealing a decisive disabling blow. If you have the time to choose, choose an effective weapon but don't worry about niggling paper differences between different defensive handgun calibers and bullets (Hydra-Shok or Gold Dot? .40 S&W or .45 ACP? Paperweight or ashtray?). If you don't have the time to choose, then grab the nearest effective weapon (it might even be your fists, elbows, knees, feet, or head) and use it with maximal efficiency as above.
So... in answer to your question, if all I had was a .22 pistol then I
darn sure would make it count. Maybe I wouldn't be able to stop the attacker if I emptied all 10 rounds from a Mark II into his chest at a few feet. If he kept coming I'd thrust the barrel into his eye socket with all of my adreneline-supplemented strength. That ought to slow him down a little bit, and then I'd punch and kick him while he worried about what was sticking out of his face. When I thought I could successfully run away, I'd do it... until then I'd pummel him until I could get away.
Poll