I usually use a rosin bag when I start practice, just to make sure I have a good grip on the ball when I start. I always lose the ball when I first start warming up if I don't use some rosin. After that, I just use a dry ball, and I seem to have good luck holding on to the ball. My hands (among other parts of the body) also sweat a lot while bowling, so I always have a dry ball around.
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-Corey
What, like the back of a Volkswagen?