I'm in the same boat with my 10 year old, he is wearing me out about a bow. I know his first question is going to be "Can I kill a deer with it?" So how much kinetic energy is needed for this, and how do you figure it? Or maybe just a basic rule of thumb for how much is needed? If it is not possible for him right now and he needs to work up that is fine, just where does he need to work up to? What level is acceptable?