I see now that the tube steel is Röchling - Röchling Spezialstahl, Röchling Elektro-Stahl oder Röchling Sonderstahl R7L.


https://doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=320716&page=1

Hochachtungsvoll

Raimey
rse