I've been looking for this thread, from 2012. Jack posted an image of Dr Gaddy's vertical gauge
https://www.doublegunshop.com/forum...p;Board=1&main=26014&type=thread

I searched but could not find Dr. Gaddy's wall thickness recommendations, but most of the Forums have changed formats/host since he was posting, and old threads have been lost. The PGCA search function ends at 2014.

From Brian Dudley
https://parkerguns.org/forums/showthread.php?t=14438
I like to see numbers of at least around .025" minimum in the from half. Around .050" to .060" at the forend loop, and I find that most sound barrels run .090" to .100" in front of the forcing cones. These numbers are just ranges that I have found from measuring and firing different barrel sets.

A thoughtful post from Jay Schachter and Bill's instructions are on p. 5
https://parkerguns.org/forums/showthread.php?t=7889

More measurements

https://parkerguns.org/forums/showthread.php?t=15472
The least end-of-chamber MWT found
16g VHE #1 frame .094"
12g GH 1 1/2 frame .095"

https://parkerguns.org/forums/showthread.php?t=22313
"two 1 1/2 frame guns, I find .096", and .092" at the forcing cones"

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