Aside from the big brother aspect, how would you apply proof, retroactively to the millions of guns floating around America? You can't put the manure back in the horse.
I have to imagine establishing a proof house must have been deliberated by early congress'. Could make for an interesting article for enterprising writer.
More than anything, I imagine folks here want protection from dealers selling a shotgun with thin or otherwise unsafe barrels. Only two ways to do that, get a written statement from the dealer that states the minimum wall thickness 3-9" from the breech, 4 inches from the muzzle, and the thinnest point between. Or, a simple, written, no questions asked, return period and the buyer can have the barrels measured elsewhere.
I doubt a proof house would catch guns that had been artfully humped into something else.
