It' ll do fine if he keeps his shots close but here' s an idea.....
if he' s got to get them in that close, why not use a bow!!!!
He' s only 13 and he' s never shot a bow powerful enough to ethically kill a deer. He' s got a 25lber that I have him shoot just for the fun of it and to start working on his form. He is still a little young for the 12 gauge, but next year will be his year for the 12.