Sirs, I believe the attached line below compiled by me on Doublegunshop has the most complete information on Reilly every compiled. It includes SN's of about 300 extant Reilly's which include "marker" SN's enabling most Reilly's to be dated fairly precisely.
http://www.doublegunshop.com/forums/...38&nt=9&page=1
SN 1039 would have been one of the first SN's used by J.C. Reilly (the father) upon their move from Holborn Bars to 316 High Holborn in August 1835. I don't believe pinfires were around at that time. Please check the serial number again. In addition, would appreciate the name and address which appears on the rib which can help date this gun. The above doublegunshop line continues to compile a record of every Reilly which can be found. If you'd like to post pictures and information on your gun, it would be appreciated.
And Kensal I would very much like to read your article and compare it to the research mentioned above.