I would shoot #7's in factory loads or start loading TSS #9s, which is what I am having my 6 yo shoot.
Also, I'd save up and get a Knoxx Spec-Ops recoil reducing stock. It adjust to 11" LOP and really does reduce the recoil significantly. It is well worth the investment.
If you are not in a hurry you can get one from Optics Sale usually the cheapest, but their shipping is pretty hit or miss and having it in stock is an issue. Just perform an internet search and find it cheap. My 6 yo does very well with it.