Robert:
IE the Schilling.
I have no idea of the name of the pattern but do know that Schilling was the maker. His firm was perhaps the premier barrel maker in Suhl. You will find his mark on any number of better to best German guns. These barrels appeared to be alternating steel and iron.
You are correct that when the barrels are polished, they do shine like silver. Overall, that gun pictured is a very elegant one.
I mentioned that these barrel types were used in England. I know that Rigby made quite a few rifles with this treatment. Do not know if there any English shotguns having them.
I had assumed that more makers may have used it, but have never seen any but Schilling and Rigby.
Best,
John
