In my opinion damascus steel, as with all other alloys, has never reached the degree of sophisication as it has in recent decades [except for maybe the high art of the Prince Phillip, Remington, or Terrell type damascus]...Well here are some leads for anyones American damascus files...
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In 1937, there was a company in Rockford Ill. by the name of Damascus Steel Product Corporation. They held a patent for a meat cleaver, but that couldn't have been their only product...Of course 1937 is very late for damascus barrels...
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In 1856, John Nevill and Lemuel Curtis recieved a patent for simplified damascus substitute [alloy] assigned to J P Farrar of the "Damascus Steel Manufacturing Company"...kind of early for the golden age of double shotgun production, but none the less, another lead.
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Warner is from New York City

The Sachs technique or something similar has been seen on a high grade Parker
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There are several more damascus shotgun patents to be shown in the next weeks...sorry they're difficult to locate because they are pre- personal computer files...