Krupp Fluss Stahl (
Krupp Fluß-Stahl Homogeneous Fluid Steel) and Krupp Nickel Steel were both introduced (in Europe) in 1891
http://www.shotguns.se/html/sauer_information.html 1891 Sauer introduce Krupp Special steel in four different types:
1. Krupp
laufstahl2. Special
Gewehr Laufstahl, Fried.Krupp A.G. Essen.
3.
Krupp-Inerso-Laufstahl.
4.
Fried.Krupp A.G. Essen Nirosta.
Houchins states that Krupp barrels were first listed in Hunter Arms catalogs in 1895, were stamped "KRUPP ESSSEN FLUZ STAHL', but Smith doubles with Krupp barrels are rare.
1901