Correction: I'm now sure the "HK" combined stamp is that of Heinrich Krieghoff with the association of Sempert & Krieghoff.
Kind Regards,
Raimey
rse
Here's a Sempert & Krieghoff(ceased in 1920s) example by Krieghoff at Cabelas with the "HK" overlapped stamp(1st column 3 row):
http://www.cabelas.com/cabelas/en/conten...erarchyId=11899 . Being proved in 1942 I think it was made from leftover stock and post 1928 Heinrich Krieghoff used the registered Schwertanker trademark. There's a mark centered on the underside of the tube near the word "Lauf" that I can't make out.
Kind Regards,
Raimey
rse