NE,

Has anyone seen this stamp, two squares with the letter “K” inside each, before? If so, what have you seen it stamped on?

I’ve been digging around a bunch and I haven’t been able to find out what kind of stamp it is (proof, inspector, or other) or who it represents (gun manufacturer, barrel maker, or other). It doesn’t look like any proof mark I’ve seen listed so I’m tempted to rule that out.
The only tie to a manufacturer that I have seen is on a Greifelt “clamshell” receiver double rifle. I have it stamped on one of my clamshell double rifles as well but that isn’t helping anything because it doesn’t have a manufacturers name on it. My guess is it looks like a barrel makers stamp but I’d like to know if it is particular to Greifelt guns, clamshell receiver guns, or perhaps just to a particular barrel manufacturer. As there were so many of each (gun manufacturers and barrel manufacturers) operating in Europe prior to WWII researching these things can drive one bats.

I would certainly appreciate any information that you could share with me.

Regards,

Marcus