Mr Tut, a common mistake. Wall thkness cannot be measured as described. Your math works only if inside and outside dias are perfect round and concentric,not true in most cases. I wouldn't be surprised if the .0415 is realy about .030 if that .655 is correct. You ddin't say how you measured the inside.
Inside was taken with a Skeets. Your indeed correct, without having a true ability to measure min barrel wall thickness, I'm guesstimating. Proof in the pudding will be when I take it to my Smith who has all the tools. With this barrel weight I'd be quite surprised if they are only .030 Min. I could see that if they were 4 weight barrels, but these have lots of mass.
