my thank s for your interest and for your help
please make me aware of any Dreyse hunting gun you see because it will be one piece more of the puzzle.

600-900 aus. dollar will be a good price, if described as a 16 ga its probably a 0,74" and with the 14000 serial number I put this in the late 1870s.
hope I find the time this year to make something about reloading for the two most common cartridges the 0,70" and the 0,74". actually its very simple and depending on your gun law its maybe possible to change the gun for the common center fire priming. just for the case you dont want to play with the more complicated needle fire priming. but what means complicated there is no rocket science.
under my own gunlaw here I hold them as needle fire guns because they are licence free.
in the end you got the Randschlusspiegel cartridges with needle fire and center fire primer so it was a common modification beside of the guns made for our center fire shotgun shells you find out by the cartridge ectractor.