I messed with one of mine (had too many) and honestly, that core and the medium load of particles make the ball super strong out of box....sanding means you will only be able to use it on HEAVY OIL ONLY...and as soon as it sniffs dry..well....you will need to put it in the bag...
I had a few polished and had pretty good luck getting some separation between the original and the polished one....went a few feet further and had better backend....I had a few drilled where I had the same drilling on 2 balls, but one was factory surface and the other was polished, and they did give me a good separation....
To get some shine on the GP2, you will really have to hit it a few times to get the grit up...the medium load of particles makes it a tisker tougher to shine.
Clint
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Clint Daley-Owner
Lets Go Bowling Daley
Inside Hunt Club Lanes
Salem, Ohio 44460
Track Pro Shop staff
www.trackbowling.com