Hi Chuck,
I'd imagine a bunch of different things come into play. If it comes to shooting, I'd assume everything was put together as a gun and not just a barrel with a rib on it. To be honest, I'm not sure what a rib/bore center line is. Would body configuration and shooting style relate back to stock fit, not just style/dimension.
Anyway, I figure, off the rib or bore or whatever, stock dimensions could be measured and seem similar. How it emerges out of the action and where the force of firing a shell pushes on the stock might be very different, and affect styles, preferences and result.
If the stock can be taken out of the equation, then it may matter how the metal work is arranged and distributed. Just conversation Chuck. The two different over under frame styles seem to be unique to me and some guns seem to bring it all together a little better than others.
