The stiffness of the uprights of a shotgun barrel wall thickness gauge of course is an issue that is of concern to the users of such a gauge. In England I examined the shotgun barrel wall thickness gauges in various gunmakers shops during the several times I lived and worked there. Two items stand out in my mind in viewing these gauges in those shops: (1) all of the gauges I saw were built by the craftsmen in these shops---not "store bought"; and (2) all of these gauges had uprights shorter than what we see made here in North America. Some gauges I have seen in use by British trained gunmakers have the uprights no longer than maybe 10 inches, resulting in stiffness of these uprights be of little concern.

Shotgun gunmakers, barrel makers and gunsmiths of significant experience know where the thin wall area of a shotgun barrel is going to be within maybe 95% certainty---6 to 9 inches from the muzzle near the ribs.

Take a look at the photo above of the shotgun wall thickness gauge in use and see that this thin area of the barrel is within the range I just quoted as well as where it is. The range of the wall thickness of this barrel was .024''-.029".

Regards;
Stephen Howell