Thanks everyone, and any more feedback on what to try!

We will use these (two boxes) to get her shooting the gun and get it sighted in. Will move to a different bullet as I do more research. As mentioned above, we have enough invested into this hunt (and others we have planned) that the expense of bullets isn't a factor! When she pulls the trigger, I want good performance on the other end for "bang, flop" he's down!