1400 km trip though the Sahara and I'm pretty beat. But that is an interesting gun! It is pretty definitively 1889. EM was still alive. Could he have built the whole thing under license? Doubtful but one must ask. The review of the 1885 London Inventions exposition indicate it was possible. Both 16 and 277 workshops were still operational.

And I have to admit Parabola knows a lot more about this action than I ever will!