Sure.  The "RG" numbers you see associated with a ball tell you about the core.  High RG numbers generally mean that the ball is more "cover heavy".  The core tends to be taller, putting more weight closer to the cover and making the ball lope.  Low RG balls generally have shorter/fatter (sometimes smaller and more dense) cores.  These center heavy cores rev up faster and easier.  Don't forget that the cover is still far more important than the core numbers.  A super strong cover with a high RG number will still hook (not necessarily rev) earlier than a weak cover with a super low RG core.  The second ball will rev as opposed to lope, but without friction, the weaker cover won't allow it to hook as early as a strong cover.
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Ron Clifton's Bowling Tip Archive