Craig, the value is that in their countries of origin, the gun is supposed to be submitted for reproof and those proof stampings changed if there's been significant modification to the gun in question: Chambers lengthened, barrels honed so that they're maybe .010 or more larger than originally stamped, etc. So the value is, with bore and choke and chamber gauges, you can very quickly determine how much the gun has been tampered with since it was originally proofed. Or reproofed.