When they are making a ball, can the manufacturers decide ahead of time that they want to make 100 1-2 inch pins, 100 3-4 inch pins, etc.  Or is it luck of the draw?
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The clock on the wall says 3 O'Clock...last call...for Alcohol!
"I love a martini -- but two at the most. Three I’m under the table; Four, I’m under the host."  Dorothy Parker

The more pieces you have...the more complicated it gets, but imagine a basic two piece ball.  You start with a completed core. You put the core into a mold and pour the coverstock around it.  If you put the core dead center into the ball then you get a pin in ball.  If you pitch the core more toward one side, then you get a pin out ball.  The more the offset toward the one side, the greater the pin out.
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Good luck & good bowling