Even a semi-auto can be a single shot using the Barney Fyffe method. Buy what you want her to hunt with when she grows and make it fit. Having said that, I prefer a pump. The 870 would be easy to fit to her and relpacement stocks are readily available when she grows. I do like the new P-08 too, but I am at heart an Ithaca guy. The 37 is very light and handy. It fits me better that any other pump. They are not easy to find these days though and aftermarket support is lacking.