Here are a few explanations of pin to PAP distances as well as some more info on the 'Rico' layout.
The reason why the 'Rico' layout tends to be stronger in the back part of the lane is the placement of the weight hole. By placing the weight hole at 6 3/4" from the pin, creates the strongest amount of asymmetry in the ball. Asymmetry in the ball can help create continuity in the back end.
Pin to PAP placements are as such (devoid of surface prep and a weight hole):
Placing the pin at leverage or 3 3/8" from the PAP allows the highest amount of flare potential in the core. Flare potential is dependant on core strength or RG differential. Leverage or 3 3/8" pin placements generally will create more overall hook, front to back, more so than side to side. A leverage or 3 3/8" pin placement does not tend to create an angular reaction, as most think due to this being considered the strongest layout.
Any deviation from leverage, changes flare potential, as well as reaction shape.
Placing the pin closer to PAP, decreases flare potential and creates an earlier reaction on the lane and a smoother back end reaction.
Placing the pin farther from the PAP and closer to the track, decreases the flare potential and creates a later reaction and a smoother back end reaction.
Hope this makes sense and clears up questions that have been asked.
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Formerly BrunsRico