I'm not looking at the books right now, but I think something over a hundred or so are listed, but of those how many actually exist, I do not know. If yours is specifically listed (not just "close"), you have a VERY desirable gun.

I don't have an RR carbine, but do have something almost as good - an 1896 carbine from the China Relief Expedition - the Boxer Rebellion ("55 Days at Peking").