Since I know nothing about the lane conditions /coverstock / core shape, and I have to assume my style of play, I will choose a moderate grit (1500-2000) and a pin that gives me a moderate amount of roll vs. snap - maybe right of ring finger.
The more you know about your own game and style, the lane conditions you will experience, and the goal of the ball (spare ball vs. strike ball), the better you can hone in on what "the right ball layout and grit" would be for you for any particular situation.
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Dan
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Engineering * Bowling = a fun and practical application of rotational kinematics.