I was just reading some of Jack Dempsey's book that Chris posted (thanks for that Chris, great read) and he talks about punching with the outer three knuckles. I've heard this before but the coaches I've learned from have all said to use the index and middle knuckles. Dempsey's book went through a demonstration where you lean into a wall holding yourself up by your fist both ways but I didn't feel more stability on the outer three as he said I should. Maybe this is because I'm used to using the inner. I also feel like using the outside knuckles decreases your reach a little bit, but maybe I'm off on that.
Are the inner two typically taught just because they are less likely to lead to injury? Do you get more power using the outer knuckles? I'd like to hear what you guys think about this.