Thanks for the replies. Looks like I'll raise the powder charge and see what happens. First I'll have to get an assortment of bullets to try. Probably get some 250s and 300s in the same brandto see which weight it prefers, then try a few different brands.
BTW - I didn't mention it, but I did try afew Lee 360gr improved minis. It didn't care for them at all! Before we left I loaded a round ball for my 7 year old with 25 gr ffg T-7. He put it right in the bullseye at 25 yards! Never let an inexperienced kid shoot your rifle - he'll outshoot you every time.