Kevin:
It was made in Suhl between 1912 & 1923. Until yet have we been able to make a somewhat accurate guesstatement or stab and the "K" in the rhombus or rotated square. Like Mark posted, Mr. Dietrich Apel has seen the stamp before and possibly has the answer penned away somewhere. But I think we can narrow the tubeset knitter to being of the Kelber klan or the Klett klan. I think Erich Kelber to be the son of Wilhelm Kelber but I don't think he was active when your example was made. Emil Klett looks to have been active just after WWI and he stems from a long and wide family of gunmakers. He'd be my guess, but that's all it is a guess. To whom the "EK" belongs is yet to be defined, but who ever he was he put a large effort in tube knitting as his initials are found on many examples. Your longarm somewhat resembles a Merkel but not fully. They usually subed their tube work to the boys Kelber. Any other worn marks near the forend lug or on the frame may help narrow the field. Wilcke pretty much was a firearms merchant but also had to be a master gunsmith or employ a mastergun smith. The smart gunsmith who became businessmen migrated to being a firearms merchant because that was where the money was. The other master craftsmen continued in their craft and while being experts in their field became subcontractors to the trade. Wilcke may have been a wholesaler who sourced the components and then subcontracted the work. Who knows, but we are continually digging for answers in a pool that is somewhat dingy and has a lot of sand in it that keeps pouring back upon you. The main thing to remember is that there were families of craftsmen who performed specific tasks and for generations they appear to do the same thing. Gunmaking families intermarried developing sourcing lines in addition to, or along the same lines, as economic sourcing lines. Your puzzle is somewhat simple compared to some of the examples that have surfaced.

My definition of early would be from the 1870s. But of course almost all would be hammerguns. Now there's an addiction that's difficult to overcome.

Kind Regards,

Raimey
rse