Yeah, get a driller to watch you throw some shots so that he or she can tailor the reaction to be what you want it to be.
From experience, the Granite is a great ball. I've owned two of them. If you use it in box finish, you'd better have a great deal of head oil. That ball is gritty, gritty, gritty. It feels like a cinder block.
If you polish the ball, it will go a bit longer and offer a fairly strong backend move. In either state, the ball hits and carries very well. It was one of my favorite Visionary balls.
Find a good driller, get measured up properly, and have some fun with it. Just a word to the wise, however; make sure you keep it clean. That ball collects dirt and lane junk like a vacuum.
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I've only bowled 300, but I've benched 345
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