Many thanks Mr. Kipling. I have I think written the modern definitive short-history of Reilly. Diggory Hadoke is publishing part of it. The more complete short version can be read here on Doublegunshop.com.
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=436538&page=33
However, at some point I'll write it all up for an on-line publication.
Here is a post 1881 Reilly muzzle loader sold in New Zealand - SN unfortunately not published - showing Reilly continued to build what people wanted to buy at that time. - if it only had "Paris" on the rib (and not rue Scribe) then it probably could be dated post July 1885 (I wrote to the auction house trying to get the SN - records had been destroyed).
I would very much like to have the information on your Reilly guns....Serial number, name on the rib or barrels, any patents visible. I believe I can then date them within a few months...depending on the age..and it would help further define Reilly...an enigmatic gun maker whom I think I've been able to bring out of the shadows. 1855-1905 date periods will be pretty precise due to the number of guns still existing.
I have asked my friend to look at 5512. If he is not confident it can be shot, he'll return it to me. I'll consult with the board then on what can be done to get it back in the field. It is a historic gun. It has both addresses, "316 High Holborn now 502 New Oxford" which is about as definitive a date marker as one can get from that age (even if the SN is quixotic), and I want to save it (and I'm not a collector).
Nipple threads are something I'm not familiar with. I am familiar with "BSF" from my 1960's-70's days of working on BSA and Triumph motorcycles (we called it "British Strip Fine") and I still have my Whitworth motorcycle tools from that era. But before doing anything, I'll await the first report.
By the way I've discussed this gun with former Purdey gun mechanic David Trevaillon up in Maine who has given me some advice on working on the stock. It's a neat gun and I will save it if at all possible.
Me just after Vietnam with my BSA DBD-34 1954 BSA 500 single flat tracker.