That's a tough question, I was probably 12 when I was first let have a gun in the woods, but I think it depends on the kid, I recently helped at a Jakes Day event we put on and some of those younger kids used and handled the weaponry better than some Adults I've known. So I really think it's an indivdual thing parents need to conclude on a case by case basis.
I hope my Daughter is huntin'with me before too much longer...