The tighter my thumb hole, the worse I throw the ball. I get mine drilled larger, then put tape in there to get what I feel is the best feel for me. If my thumb starts to swell, and the fit gets too tight, I pull the crud out of the ball.
I was missing a lot of 7 pins to the right, and couldn't figure out why. I was hanging up in the thumb. So I took all the tape out, and now it rolls off my hand perfectly. The thumb hole is too big, but for me that just works better for my spares.
I have always had trouble getting my thumb just right, but I like to have a little bit of room in there.
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Formerly SGC300
"Never get into a pissing match with a skunk, cuz he'll piss all over you and like it."-Keyshawn Johnson on Terrell Owens