Hey ryry,
Yes they are different for all weights. Each manufacturer does things a little differently. For Track, we use the same weight in filler and shell which when we decrease in core weight, it raises the rg and alters the differential.
For me personally, I see a tremendous amount of difference in a ball that is 2.50 and 2.53 rg. My personal magic number has been 2.50 to see a ball naturally rev up off my hand without having to hit it where as a 2.53 will lope down the lane and not rev as much. Having that much differnce for me creates a different breakpoint down lane and changes how I would have to play the lane.
If you look at Roto Grip, their numbers are completely different sometimes for a 16 to 15 and then 14. It is apparent they are designing balls to 15lbs which is still the most popular weight sold in high end performance.
I've been throwing 14lbs for 4-5 years now, if there are any balls that you are interested in, let me know and I'll dig up the rg's and diffs for you if you want. Thanks...
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Rick Leong - Ten Pins Pro Shop
Track Intl. - Amateur/Pro Shop Staff
Vise Inserts Staff
www.Trackbowling.comSee profile for Track Ball videos
*El Presidente of the Track Legion