Drew, would you say that those wall thickness numbers would also apply to Royal Steel barrels? I just bought a typically-rough F grade, #86627, with Royal Steel. By what I have read, this was made the 2nd year that these were available, in 1900. For now, I don't intend to have the barrels opened up, but they are pretty rough. I will let a pro evaluate how feasible it is to fix this one up.