Joe, reference your question on minimum thickness, from "Modern Sporting Guns" by Christopher Austyn (formerly head of the Sporting Gun Department at Christie's in London):
"There is no legal minimum thickness for a shotgun barrel, although the British Gun Trade Association RECOMMEND 20 thousandths of an inch as a general minimum." (Emphasis the author's.)
I'd certainly heed the recommendations of experts such as Hugh when it comes to minimums at various distances from the breech. However, I will add this bit of food for thought: When you get within a few inches of the muzzle, does it make sense to concern ourselves overly much with wall thickness . . . when we don't concern ourselves with actual HOLES in the barrels (porting)?
