A guy showed up years ago at a local Rendezvous with a gun very similar to this one in .60 cal. The rifling was the same, as was the ramrod, and the Damascus barrel. I believe his was made in Ireland. There was a big dust up over shooting a Damascus barrel, but after close examination it was determined that it not really Damascus steel at all, just a nicely done imitation finish. It was not as nicely engraved as this one, but was in pretty good shape.
Quality Damascus is not an issue. Its the cheap poorly made Damascus that came to the US in the late 19th c that caused the problem. Shotguns selling for 2-4 dollars apiece could not be expected to have barrels of any quality.
Damascus shotgun barrels are still made in England IIRC. Proved for Nitro.
But people need to know what to look for in a Damascus shotgun or rifle barrel, dents in shotgun barrels can break we weld in the other barrel as well. Rifle barrels look for pitting that might be deeper than one thinks. I would not shoot damascus with any proof other than English. Parker used first quality English machine made Damascus in the late 19th, early 20th c. But most used lower grade steels..... The best English machine made Damascus was fully equal to "Whitworth steel" in the mid-late 1890s. Read this in "The Gun and Its Development" W.W. Greener. Mine is from 1896....