The real value of a proofhouse, to the buyer of a used gun, comes in those various proofmarks. Was my gun originally 2 1/2" or 2 3/4"? For about the last century, one glance at British proofmarks would answer that question. American guns . . . you might be able to find out, IF the company's original records survive. Otherwise, you have a pre-WWII American gun, you're guessing whether it left the factory with short chambers. And very few gunsmiths who punched out chambers bothered to mark the gun with the new chamber length. Much less when the work was done.
Proofmarks also help date a gun, which is otherwise difficult to do unless company records survive. (Down to the month and year, in the case of many German guns.) Which again helps tell you--if it's not otherwise indicated on the gun--whether it had short vs 2 3/4" chambers when it left the factory.
Lagopus, you don't have total regulation of your system by the Gun Trade. Surely they don't run jails for those who violate the rules of proof. The gun trade may set the rules, but it's your police and legal system that handle enforcement. Our gun trade also sets rules. However, those rules no longer apply once the gun goes onto the second hand market. That's where our system--or lack thereof--provides less peace of mind than yours.
