Billy;
Top of the day to you! I agree muzzle loader with .50 would do him okay! I say this because it was a draw back with me in august 2006 I had open heart surgery! i was just getting my bearing's back and was kinda stay in away from the muzzle loader because no matter what anyone said I thought it would kick too much for me and I was very reserved about even using it for fear of open up chest again! But one day Frog hunter my husband said you know you'll have to get over that fear! So Yes we went out to the range and zero her in at 50 yards! I did just fine and now I'm ready to go again! But i understand your son ,I too have a 10 year old daughter whom right now shoots 20 gage and has a 410. Then Our 6 year old son shoots 410 and 22 he likes his 410 he Say's 22 abit much for him right now! I guess you had to be there to see expression on his face at the skeet and trap range! LOl
Have a Merry Christmas and Happy New Year
Mrs. FrogHunter