Brunswick''s 13lb balls use the generic core, which basically is a light bulb shaped core!
From Brunswick''s website:
Lightweight Engineering
At Brunswick, the unique core shape of each individual ball is used for weights from 14 to 16 pounds.
This approach to lightweight ball engineering provides bowlers with consistent ball reaction characteristics
across this weight range. At 12 & 13 pounds, Brunswick uses a generic core shape with a RG-differential of 0.044.
This differential is close enough to the 14-16 pound shape so that the same drilling instructions can be used.
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"Train a child up in the way they should go and when they are old they will "Get MOTIVated, with a Big B cause a Storm''s a brewing and not turn from it.
Bruce Campbell
USBC Bronze Certified Coach
IBPSIA Certified Technician
Originator of the -35deg x 25 leverage drilling!
http://www.motivbowling.com/products/2/http://www.stormbowling.com/products/ballshttp://www.rotogrip.com/products/balls/Edited on 5/13/2010 11:34 PM