Maybe someone is dumb enough to export guns out of proof but it has to be only a matter of time before he gets caught. Too many barrel wall thickness gauges out there and people know how to use them. So if you just bought a gun that is out of proof and it was discovered by your gunsmith while he was checking the gun out what would you do contact the seller or contact the exporter unless they are one in the same?

Who would risk it for a few pounds shipping and handling or even a few hundred pounds profit on the sale. If caught you stand to loose so much more than that.