".22 For self defense. Yay or nay? "
Well, a .22 RF would be a lot better than throwing tomatoes but consider that the value of a 'double tap' to the head started with Europe's panty waist 9mm. The question is not can a .22 kill, that's certain; the real issue is how fast will the troll collapse; he might need only 3-5 seconds to do other people some serious or lethal harm - including YOU! - but it would be better than a pocket knife!