Tell him congrats
My first muzzeloader deer was with a white 54 Bison when I was 9. Apparently a 540 grain bullet and 110 grains of pistol powder was what my dad could come up with for a youth load lol.
Job well done young man. Hunting will be something to keep you busy for quite a while. The number of great people you will meet will continue forever. Keep up the good work !