....It's true that any tube (or pipe) whether it be a Damascus gun barrel or modern made product contains eccentricity. It's unavoidable even with the best process technology has to offer. Locating and quantifying eccentricity can be problematic regardless of the method used but, this method can detect eccentricity....
....The only downfall is trying to determine which side of the barrel has the eccentricity. We know it lies at point B but is at the top or bottom side of the barrel or both? Does it really matter?....
I think there're manufacturing eccentricity tolerances that are acceptable. What I think folks are looking for is how the tube is changed due to external finishing or refinishing, and the various chamber, forcing cone and honing changes that can happen to the inside of a bore.
An eccentricity that might have been plenty safe could become, or a new eccentricity created that may be too thin for safety on a very small part of the barrel. I think, as was mentioned a bit ago, that there are good reasons to know if the average wall thickness involves one wall of that particular measurement being too thin.
It doesn't take one bit away from your project, and as you mentioned, you're working with it and figuring it out. If possible, I'd think make the internal contact have as small a surface area as possible so there's less chance of bridging over a low spot. Thanks for all the time and effort.
