Damascus and twist are maybe not exactly the same thing, but they are similar enough to be the same. Damascus typically uses two different types of steel, twist steel barrels used one type of steel. Both involve twisting wires together and wrapping them around a mandrel and the wires are forge welded together. Used to be a common way of making shotgun barrels. Another similar method was laminated steel, where the manufacturer took a long sheet of metal, wrapped it around a mandrel, then hammer forged it, welding the layers together. In the black powder era, it worked and was sufficient because of the low pressures involved in shooting BP with mild charges. As soon as smokeless powder showed up, twist, Damascus and laminated barrels fell out of favor pretty quickly.