Jamie, I have a buffalo ulna that, with the right muscle, will drive flakes. You might want to try to find one of them. They are a good bit thicker,so narrow notches are still in question.
I never have been good at notching,I struggle alot with it. Just started working with antler punches and must say it does take some getting use to.
Also been trying to use hammerstones exclusively and man does it get frustrating!