A damascus barrel is a barrel made of damascus steel, which is steel produced by hammering two different steels together. The twist refers to the pieces of steel being twisted while they are hammered, which produces the distinctive pattern on the steel.
The Benelli Supernova does not come with a damascus barrel as a factory option. However, some custom gunsmiths may offer aftermarket damascus barrel options for the Supernova.
You don't.
Not.
Damascus barrel (in French).
Damascus is a type of steel used usually of older firearms and tools
With the serial number that you provided,your Ithaca double barrel shotgun with the damascus barrels was produced in the year 1900.
Impossible to answer without knowing make and model.
it is all swirly
Yes.
Those early Belgian guns are generally considered wall hangers. Most have a form of twisted-wire barrel construction. If yours is actually 'Fine Damascus' and not actually laminated steel, and if the engraving is better than typical it might bring $200-$300. If it is the standard JABC (just another Belgian clunker) it will top out at $150 as a mantel decoration.
I'm not aware of any shotguns ever made with two barrels twisted together. If you are refering to "Damascus Twist" barrels, you need to learn a lot more about guns before buying one. Here is some information for you...please note the part about it not being safe to fire a Damascus barrel with modern powder. Picture an onion after a fire cracker went off inside it. http://www.hallowellco.com/damascus_twist_barrels.htm
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.