This from the Griffin & Howe site:
http://www.griffinhowe.com/abbreviations.cfm
A rule of thumb states that the minimum barrel wall thickness should be .020" in a 12 gauge gun.

From the PGCA site:
http://www.parkergun.org/forums/forum1/595.html
We who shoot Damascus barrelled guns look for a minimum of .025 wall thickness...

A real smith will no doubt set us right (but I thought it was more like .030")

Last edited by revdocdrew; 11/27/06 10:55 PM.