I started at age 9 pulling 38# never had a close enough shot, not sure about penetration. however i was stuck in a tree at 9 by myself i could shoot great but had no ability to make good judgments on shot, as long as your son doesnt have to learn the hard way like i did he should be ok. I almost gave up because i had little help, thank the lord i didnt bowhunting is the best times i have had in the woods. hope your son is the same way some day. props to you as a dad for being involved thats what makes this sport stay around for all to enjoy.. Good luck