Tribe thanks for the response and I agree mechanics, location & practice are the focus. His travel coach is a former D1 4 yr starting pitcher so he is getting solid instruction on a weekly basis. He has only brought the gun out twice in the past 1 1/2 yr to gauge where the boys are at. By no means am I trying to get in my sons head about his velocity. This question was purely to satisfy my own curiosity from those of you who have been where I'm at now. I know there is no formula, or definitive answers, I was more looking for a baseline of where your sons were at in 5th-6th grade level.
I can't even remember because it's not important. bb-Dad has said it best, this is a god given talent and nothing you can do can top that, other than provide good instruction and make sure that you do all the things for a young pitcher that you can control (mainly overuse) so when it really matters he will be healthy.