Pin length is the distance between the pin and the CG which is marked by a round punchmark normally. The PAP is your positive axis point where your ball revolves around during the lane. If you found it out, you could put a piece of white tape on it and you would see it going down the lane at least for a couple of feet staying in the same spot making a circle or something.
A rule of the thumb, the longer the pin length like 4-5 inches generate more length and backend whereas shorter pins like 1-2 promote more earlier and smoother backend. The MB, from what I understand, is only of importance in assymetrical cores. It influences the motion of the ball in the backend whether it be smooth or snappy.
If you have a good driller, ask him about it and talk to him about your style and what you want the ball to do. I've learned lots just from talking to him and from reading topics on this site. If you do a little research, I'm willing to bet you could find a topic like this in more detail. Go to options and show a 120 days worth of posts and you can read back for some time. It's gotta be in there somewhere. And right now, I'm getting tired of typing.
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So many bowling balls...So little time.
