I picked this round up at a flea market a couple years ago ($15) but I don’t know anything about it. It has a coiled brass case with iron washer rim held on with three rivets, copper battery cup primer. HOTCHKISS PATENT PARIS is stamped along the edge of the foil at the seam.
Case length: 4.736"
Rim dia: 1.873"
Base dia: 1.647"
Neck dia: 1.477"
The projectile appears to be iron with a forward driving band, or possibly a bore rider (it is 1.454"), and a rear driving band (1.503"). I had to clean a bunch of rust off. I did not see any markings amongst the pitting.
OAL of the round is 7" minus the fuze.
The fuze is not original; I made and installed it because I thought it would look better with a fuze in the nose.
Any information appreciated.