From the shape of the fences and the fit of the extractor, might it be a conversion from pinfire? A photo of the top of the fences might confirm it one way or the other.
I do have an unnamed single 10-bore pinfire fowling gun with a Francotte-marked 49.7 false-damascus barrel, and from the proof marks it dates somewhere between 1877 and1893.
(OK, after seeing a photo from a different angle, definitely not a pinfire conversion, but an original centre-fire)
Last edited by Steve Nash; 04/08/19 06:31 PM.