kotm -- Thanks for the reply.  I'm glad to hear this is a complicated subject, I'd hate to think I'm having this much trouble grasping a simple concept.  But if I can understand it, it will make me a better driller, which is what I'm looking for.  Back to some of my earlier thoughts.  First, are we all agreed that any pin position other than dead in the track migrates the core angle toward the horizontal position?  And that it is this core angle to the PAP/NAP "axle" that determines the total flare?  A pin position on the PAP would result in a 0 degree (horizontal) core angle.  And a pin position at 6 3/4" would result in a 90 degree (vertical) core angle, both in relation to the ball track.  It still seems to me that a ball with an intermediate pin position, such as 4 1/2", should have more total flare than one with a 3 3/8" pin position, since the 4 1/2" position results in an initial core angle of about 60 degrees which will then migrate through the 45 degree angle ("maximum" flare position) on its way towards horizontal.  And I've read some theories that say that the ball begins to flare even before it hits the lane surface, so that the 45 degree core angle layout may have been reduced before the ball has a chance to react from lane friction.  This agrees with an observation I've made that a bowler with a high track on a non-flaring ball has a lower initial oil ring when using a flaring ball.  I don't know if all this makes enough difference in ball reaction to worry about, but I would like to understand it.

"this is what some layout techniques (like Calhouns sweet spot) try to emulate in symmetrical cores."

I'm not familiar with Calhouns sweet spot.  Do you have any information on it you can send me or is there a web site where I could read up on it?  Thanks  --  JohnP