Zimm
If you're referring to the Zulu or Hunter trade brand shotguns weren't those converted in mass by the Belgians from Franco-Prussian War surplus 1867 French 17.8 mm Trabatatiere breech loading battle rifles, which in turn had previously been converted from 1853 and 1857 caplocks and even some 1822 French flintlocks? I had originally thought this was what you had suggested, but this one here is still a caplock and the hammer shape is not quite right for a French battle musket of that period, perhaps it was replaced sometime during its long life. I just past on an excellent condition Zulu shotgun recently for
$175. If only these old gals could talk of their adventures in Algeria, Indochina, and finally America.