This comes up every once in a while just about everywhere.

To use a 22 LR for defense against human-sized predators would require a magic bullet to be reliable. If you have to use a 22, try to use a HV lead round nose or copper washed bullet modified to have a partially flattened and cupped tip.

I can testify from experience that the Accurizer, which was used to modify the bullet seen above, works very well at improving accuracy but they may not feed reliably in some autoloaders. The improved terminal effect on small game is impressive. I've never tried it on a human being and never will unless the only alternative is harse language.