If you haven't read this book, I recommend that you do. Gary Kleck started out trying to prove that gun ownership in America was a bad thing, but what he found when he looked at the statistics told him a completely different story. Below is a graphic from his book which shows the rate of injury to the victim of violent crimes depending on how and what weapon they resisted with. Look at the far right graph... I know this is from 1993, but I find it hard to believe that the statistics have changed all that much since then.