Filaman has the simple solution, if you simply must have a pointy slug, and they're available in factory loads. I don't really see the need for them in most cases, and especially for a kid whom I imagine will be encouraged to take sure shots at moderate range. Pick a bullet designed to expand properly at the .30WCF's modest speed, and not any match bullets that might not. I've killed some deer with the Sierra 165gr Gameking HP, which is pretty explosive, but in .30/06 and maybe .308.
If I were gonna be tricky with a .30/30, I'd try some of the 150gr Speer Gold Dot bullets designed for the .300 BO. They should expand at lower velocity, allowing you to reduce the powder charge a bit if the girl is recoil-sensitive, and the 6.5s I'm using in my Grendel are pretty dang accurate. Reviewers on MidwayUSA say a lot of good things about the .308 too.
