Well .... Here goes, and I hope this makes some sense.

I started with a .410 bolt action, 3 shot Mossberg with a "Poly-Choke" that Santa Claus gave me for Christmas. I was just over 8 years old. Yep - I'm old enough to have used paper shells and the "poly-choke" ! I had a blast with this shot gun, bagging countless squirrels, rabbits, a few ducks and more nutria than my mom ever wanted me to bring home. Having said that, I'd go to the 20 ga. the 20 ga. is just more versatile.

The key, in my opinion, is to find a good fit. A kid all stretched out, because the length of pull is 2-3-4+ inches too long or the weight way forward distributed or both, will not have a fun time shooting. Also remember, the lighter the weight of the shot gun the more energy your son will have to absorb. It's a Newtonian Physics thing !!