Here is a similar tiny K on the lug of the massive 6-frame 12-guge Quality VH the Puglisi had some years ago --
6 frame 12-ga 3.jpg
I have also seen that tiny K stamped in the space between the lug and the cocking hook, but can't lay my cursor on a picture right now.
I have recorded a very tiny J.S on the lug of many hammer guns and some early hammerless ones --
42647 14.jpg