I recently had a guy ask me about LC's with the barrels made out of steel reclaimed from Battleships. I have never heard of this. I suspect that it falls into the category of Urban Legend, but as the saying goes with LC's you never know.

We do know a few things

Carnegie and Bethlehem Steel were licensed to manufacture Krupp steel plate in 1897; New York Times Nov. 7th, 1897
http://query.nytimes.com/mem/archive-free/pdf?_r=1&res=9A00E5DA123CE433A25754C0A9679D94669ED7CF

If either produced Krupp marked shotgun barrels, or if the plate was converted post-WWI to barrel material for U.S. makers (Ithaca, Fox & Baker were still at it) is unknown.

Immediately post-WWI “Fluid Steel” barrels used by U.S. makers, including Hunter Arms, were primarily AISI 1030 or 1040 Carbon Steel, possibly rephosphorized.

This is interesting
http://www.combinedfleet.com/okun_biz.htm
The steel was a slightly improved form of the original medium-carbon (0.2-0.4 percent carbon) nickel-chromium steel introduced in 1894 by Krupp and later forming the basis of all high-grade armors made of steel even today by all nations. Wh n/A used some molybdenum to improve manufacturing results and was slightly tougher (crack resistant) than the original "High-Percent Nickel-Steel," also called "Krupp Soft" or "Quality 420" (Krupp's own label) steel, used through the end of WWI.

The U.S. only lost one battleship in WWI, and it's still under water
https://www.livescience.com/64281-wwi-warship-sinking-explained.html

The USS Maine was the only battleship sunk in the Spanish American war; February 15, 1898. Maybe that's where Armour/Armor steel, introduced that year came from?!

Not sure how the industry operated 100 years ago. I suspect alloy control was a bit tougher when mixing all types of scrap. I learned another interesting story last summer when visiting the Orkney Islands. German sailors scuttled their entire captured fleet in Scapa Flow in 1919. We were told that much of the salvaged steel wound up back in Germany and was used to build their WWII fleet.