What is the difference in a damascus barrel?

Damascus steel is made by folding a mild steel together with a high-carbon steel to make it stronger, and gives it a pretty pattern. Problem with Damascus barrels is that, while they work fine with low pressure black powder loads, modern smokeless shotshells are likely to cause the barrel to rupture, which is bad. If a shotgun has a Damascus barrel, it's very old and probably just a wall-hanger.