Krupp & Sauer were very, very chummy and from what I can glean the actual phrase of the period for the protection for the Sauerwerks's sole right to manufacture tubes of Krupp's 3 Ringe Stahl is "Kruppschen Gewehrlauf-Sonderstähle" and I'm not sure when the advertising on the tube reflected Krupp Spezial Gewehrlauf Stahl Drei Ringe.

Kind Regards,

Raimey
rse