Only if it has been untouched for the last 110+ years, and it isn't a Spanish knock-off (which is probably case, whatever it is).Sorry FrankenMauser but way wrong caliber for a R&G.
I would bet that somewhere on it there is an oval with E L G inside. Look at the face
of the cylinder with a magnifying glass. It's a sort-of-close-but-not-quite copy of
a British Bulldog or RIC (Royal Irish Constabulary) revolver. As Mike said--caliber can
be one of many, all black powder. I've got one in .442 Webley. Fun to shoot but a
bit of a pain to reload.