I have a Rule GP2 drilled with the pin right of my ring finger, with the Mass Bias marker about 4" right of my thumb (out near my VAL). It has an extra hole, and I clean it regularly with Clean and Dull. I left the surface at 1200 grit, and this ball handles virtually any extremely heavy amount of oil that I see. Along with Charlest, I would agree that it is best to try the ball at box finish first and then adjust from there as needed.
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Jeff Voght
PBA Eastern Region Member