my graduate work was in econometrics, stats. I love a good linear model. And a person could probably build a pretty good model for sxs shotguns and double rifles. The variables that influence value outcomes or predictions are not many and are already pretty well known. This would not be a tough exercise. Some of the most important variables have been listed above. The thing I think about most is "When do I get to take this gun hunting?" And that act of hunting with a well made and purpose-driven gun is the greatest return on investment I could ever have.
Taking a deer with an old English double rifle, where the immediate second shot was needed, is really cool. I get major satisfaction from that

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