I agree with Rookhawk. The Hosford gauge is the way to go, but one has to understand the data it generates. It is real good for measuring the depth of pits too. Pooch, I see in your biography you work for Cabelas. Surely, as many English guns and others going through Cabelas, they have a gauge. If not, you should be able to talk them in to buying one. They are a very useful tool and pretty easy to use. I wouldn't buy a vintage gun without measuring up the barrels. It is clearly the smart thing to do when contemplating a purchase of any old gun.

Socialism is almost the worst.