Hitting the pins. Mass/speed/shape are for naught if you miss. A weirdly weighted down pin probly won't react "as planned" every time. Saw a "perfect" low center hit pin flip up in the air & land standing up right where it started. Things like that are why BP is hands down the most fun event for me. The old timer that got me "forced me" to try it, even though all I had that day was a 9mm semi, showed me that it DON'T MATTER what you use. FUN IS FUN, regardless.