I love old doubles, and a big reason why is their damascus barrels.
Gunmakers started using damascus in the 1500’s. By the mid 19th century, barrels built from it were the absolute finest available and incredibly beautiful. They were also tough to make, requiring a ton of time, manual labor, and skill. Consequently, they were by far the most expensive part of a gun.
The pics you see here are of a salesmen’s sample for a damascus-steel shotgun barrel. Basically, a barrel like this is build in three steps:
1: Stacks of various metal, sort of like club sandwiches, were hammer forged into ribbons
2: These ribbons are twisted and hammer forged into a single strip
3: This strip is twisted around a mandrel and hammer forged into a tube