Porter,
I second the above statement. I tried a .410 with my 5 yr old son last year and it was to much gun. This year he wanted to shoot his first duck, so I cut off the stock of a Mossberg Youth 20 and added some padding to help recoil. Did it thump him when we practiced shooting old duck decoys, sure did. But after a few more shots and getting it shouldered better, he was good. He was nervous until the first duck died. Same thing on the turkeys this year. We let 2 gobblers walk at 20 yards because he was nervous about the gun. We talked more about it, and I let him know the prize far out weighs the kick and you will never feel it shooting at a turkey. He killed his first one a week ago. Walking back to the truck he told me, "Dad, you were right, I didn't feel anything shooting that turkey." I just explained to him that we need to put enough "kill" on the turkey if we are going shoot at one. He always had the option to just go with me another year, but after I shot my first bird of the year with him, he would have nothing to do with waiting. Good luck, and thats awesome that you have the youngster out there!