I will not agree with this... people who want to murder will find ways to do so. If you'd like to discuss a time before guns were invented... do you think there is more or less deadly crimes? If your answer is no, then you aren't thinking about midevil times, or during the height of the Roman Empire... More people were murdered than any time in history... but I guess because it was done with swords, knives, and blunt objects it doesn't count...
My point is, PEOPLE WILL FIND A WAY TO KILL EACH OTHER. take away guns, and we will use other means.. whether it be our cars, knives, 4x4's rocks, you get the picture.