My son started with a single 410 at 10 years old, after half a dozen matches he switched to a 12ga double and said he wished he never had the 410. The heavier gun with light loads makes all the difference in the world. Try and find a used Stoeger and cut it down to 13 to 13-1/2 so it fits. That makes handling the gun much easier for the kid.
If mom has a 100 that is the Cadillac of light sxs, if its got a butt pad on it take it off and let the boy try that. Honestly if mom has the SKB 100 that is your answer right there. Let the kid use that for a while to see if he likes the game. Then consider getting him his own gun.
