Since this seems to be the thread for it, I have a mystery magazine. It came via GB many years ago and has a 15-round capacity.
Overall
Whats interesting is that the lug that engages the magazine catch is soldered on by the edges, I can see light underneath it and there is no sign of any thing inside the magazine body
The bottom has a rather large sliding floorplate
Shot of the follower from the top, I think its been repurposed
The only clue I have to its origins is this "J" stamped into the toe
Floorplate and follower, while the metalwork is excellent, the follower looks like someone did a lot of trial and error
Back of the follower, there is no corresponding groove in the magazine body so thats very much a sign it came from elsewhere.
Anyone seen anything like this?