It comes down to price & Mr. Augustus Reichwald, Krupp's London agent, explains it best. There is quite a separation in cost between the Krupp Special Gun Barrel Steel(3 Ringe Stahl) & the Krupp Flu-Stahl; hence the difference in technology. I have very strong suspicions that a tube stamped with Prima Flu-Stahl Krupp Essen most likely has origins in Liege or possibly Ferlach.

Kind Regards,

Raimey
rse