If you want an neat talking piece and something with some history, a Zulu might make an interesting piece to hang on the wall, but I don't think I would shoot one.
I'll try to clarify the history. When fixed cartridge rifles were introduced about the time of the U.S. Civil War, every country was suddenly stuck with hundreds of thousands of obsolete muzzle loading muskets. To try to salvage something out of the mess, various means were developed to convert those muskets to breech loaders. In the U.S., it was the Allin conversion, a front-hinged breechblock we call the "trapdoor." In Britain, the conversion of Enfield muskets used the Snider system, and in France conversion of their Model 1857 musket was done with a system they nicknamed the "snuff box" or "tabatiere". Those conversions were issued to their respective armies, some in small numbers, others in large quantities.
After a while, it became obvious that conversions were not working out too well and those nations went to rifles made from scratch as breechloaders. Then they sold off their old conversions to arms dealers.
The arms dealers resold many of those conversions "as is", but there was a demand, especially in Africa and South America, for cheap shotguns for use by the natives. So the arms companies took the old conversions, removed the rifled barrels and installed shotgun barrels, thus creating the "Zulu" shotgun.
So, yes, the guns were ex-military ("milsurp" in today's slang) guns, converted twice, once from muskets to breech loading rifles by an army, then again from breech loading rifles to breech loading shotguns by civilian gun dealers.
As noted above, the ones with back action locks were originally French muskets.
HTH
Jim