doublegunshop.com - home Forums Thread Like Summary - Barrel Wall Thickness Gauge

For a decade or more there is from time to time discussion about shotgun barrel wall thickness gauges. Some of you may want to build one and they are quite easy to build if you have a metal lathe or access to one. More than 20 years ago I built one that has served me well and our colleague Dustin has agreed to post 4 photos of it to this discussion thread.

Such a gauge on the style I built can be made for maybe $50.00 (instead of the $650.00 Galazan price) and it requires very little lathe work which can even been done with a 7x12 inch Asian lathe as the upright posts are made from precision ground drill rod (which requires no lathe work). The only lathe work is the drilling/threading of the post bottom holes and the turning of the top of the upright posts for the brass tops, the brass top pieces which are set in place with a tight fit and secured with thread locker fluid upon the upright post and the turning of the brass spring loaded plungers. The brake rotor base is free from an auto shop junk heap. The spring plunger design used is an alternative to the traditional lever spring tension used by most builders. A hole opposite the plunger is threaded and a threaded brass plug is inserted with the steel spring for the plunger; and after checking that the plunger works properly and moves fully into the plunger hole, the brass plug excess is cut and filed/polished smooth to the same diameter as the upright plug--secured with thread locker or super glue. If you ever need to remove the brass plug you drill two small holes for a spanner such as you use to remove striker discs then heat the upright post to 350 degrees in the oven and back the threaded plug out.

You will notice that a 5-hole brake rotor is used as the holes are ideally spaced for the upright posts. Cover the bottom of the brake rotor by gluing on leather or heavy felt.

The larger upright is for 16/12 gauge and the smaller upright for 28/20 gauge.



Kindest Regards;
Stephen Howell

For Bushveld:

As you can see above I have pulled one of the drawers of my workbench open and placed a piece of plywood upon the drawer and positioned the wall thickness gauge on the plywood. This allows me to look down onto the gauge for maximum visibility. If you look to the right of the plywood you will see the white drawer pulls of the other several drawers

Dustin; Thank you for posting the above photo.

Stephen Howell

For Bushveld:

The wall thickness gauge in use:

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