I'm going to assume that you're just being obstinate here. Is a .22 a defensive weapon? Sure. Like all have said, it's better than nothing. The question though is more along the lines of would you prepare to use a .22 as a defensive weapon. I think all agree, that's not a good plan. If the SHTF and all you can get your hands on is a .22, then you're way ahead of the guy that can only find a rock. Clearly, you would be better off if all you could find was a 9mm, even better a .45, even better? a Ma Duece all mounted up. But, not in your mind. The only physical difference to the recipient is one quarter of an inch. That's all the damage done. One half inch hole for the deuce, a quarter inch hole for the .22. I would suggest that getting hit anywhere center mass with a .50 is likely fatal or at least puts you down. A .22? most center mass hits probably aren't fatal and many don't even put you down. It's physics. F=MA(2). The difference between projectiles isn't only the diameter of the projectile. But, you already know this.