Thanks, Raf! Would be interesting to know the location of the find and its cultural and historic context, especially considering that during the period in question, the lands of the eastern Baltic and the Slavonic territories to the south and east were a crossroads for invasion and rule under different crowns.

This is an interesting one. Mainspring bears down on the front of the cock's foot, as on the Kremlin example I posted above. Snaphaunce configuration, with a vertical post on the pan indicating a pivot for a (matchlock-type) manually opened pan-cover (which is also seen on some primitive Scandinavian designs).

Do you have Yuri Miller's Russian Arms and Armour ? More princely examples of Russian snaplocks in the Kremlin Armory, and during the period in which they were in vogue, there was quite a spectrum of design variations. You see lockplates with a bulging contour on the bottom imitating the style of wheellocks, external and internal mainsprings, decorative and stylistic touches echoing Scottish, Dutch, and English snaphaunces, etc.