Matchlock maker mark

[Bayowolf]

I recently received a matchlock I picked at auction a few months ago. Originally from the Zeughaus Berlin. There is an identical example in the Deutches Historisches Museum. The link is included below. They indicate it is ca. 1670 for whatever that is worth. My example has a deeply struck mark on one barrel flat. Three keys? Perhaps? Does anyone recognize the mark?

https://objekt.db.dhm.de/objekt/MI004621

[adrian]

Have you searched through this thread for that mark;

MARKS OF ARMOURERS, SWORDSMITHS AND GUNSMITHS

[Bayowolf]

Yes, I have. I don't see it there. Of course I could always have missed it.

[DaleH]

Rear sight is not original and is installed backwards.