Nice job, Hank. However, wall thickness cannot be determined using your method. All you get is the average wall thickness when you divide by two. One could be .010" thinner or thicker than other, and there's no way you could know that with your method. There are almost always thinner and thicker areas on these old barrel sets, due to the hand striking that was done during their completion.
The proper way to map wall thickness is using a specially made wall thickness gauge. You can google that name and read all about them. Probably even watch them in use on "YouTube".
All my best, SRH
