The thickest and thinest walls are where they measure that way. No fair guessing. If it is a gun you are writing a check for, you measure everything; up, down, left, right, front, back, and all combinations. I went to an auction to buy a cased pair of pre WWl William Evans sidelocks a few years ago. The full measurement of both barrels in both guns took me and an assistant maybe fifteen minutes, probably less. If the measurements had been bad, it could have cost me a fortune if I had bought the gun. As it turned out, the barrels were as proofed, unmodified for bore or choke. How would I have known without $200 worth of bore gauges and wall thickness gauges?
