Yeh, I think a severe restriking of the barrel exteriors in the chamber area and/or lengthened chambers would make w/t important in that area. And I don't know that I'd rely on a chamber diameter measurement made with a T-gauge and subtracted from barrel OD at the corresponding external location divided by 2 to give me the wall thickness. You gotta watch those barrels where the breeches are shy of the balls!!

jack