Jeff,
Bob H is correct. We were discussing a Labyrinth. Morich said it was 500 grit compounded. Well, as you know 500 grit is veyr dull and grabby, but the ball wasn't I email Morich for an explanation. Fred Carroll, one of the nicer bowlign guys around, explained this is really a Columbia term. It meant a compund-type of factory "slurry" was used to get the ball smooth and finish it to about 1000/1200 grit smooth finish, like many of Track's power balls these days.
Yes, it can be very confusing.
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"Just because you can do something does not mean you should do it."