This had to be a re-run advert in 1922 as by then makers would have been touting Inerso-Laufstahl & NiroSta:
patent for the Krupp Stahl NIROSTA(Nitro Stahl - Nichtrostendender) was filed by Krupp on Oktober 17th, 1912.
NIROSTA(NIchtROstendenSTAhl) - Trademark - 1922

Nirosta 18-8
Nirosta 19-9-4
Nirosta V-2A
Nirosta V-2A Extra

https://doublegunshop.com/forums/ub...Words=nirosta&Search=true#Post405086

But all of the run of the mill Krupp tubes find their origin in Liège, where Krupp, Sauer & other's filed patent protections. I am really not sure @ all how Sauer turned out the Spezial Gewehr Lauf Stahl 3 Ringe tubes????? I will have to dig a bit to see if Krupp filed a Patent Protection for the 3 Ringe.

Ah, we'll have to get Hause down here in the Basement to provide some percentages / statistics......


Serbus,

Raimey
rse