Hope I am not damaging the thread about the fence screws too badly, but does the Anson & Deely Patent Use number 1385 as stamped on the action flats of my fairly old Greener Serial No. 19979 refer only to the latch for the fore end? When was this patent issued?
In my experience of A&D guns, the individual mechanisms in one of their guns carried the Patent stamp and or Use number associated with THAT mechanism. So the Gas Check carries it on the breech face, the action carries it on the action flats, the Deeley & Edge forend catch is stamped on the lever's side. What you need to remember is that there are several different patents at work in the firing mechanism of an A&D boxlock, not just the original leverwork: one patent for the basic leverwork, another patent that includes the new spring shape that trips the ejectors, another that covers the 'dicky bird' safety, another that covers the interceptor sears. If no patent number is quoted (and it often isn't) the use number could refer to any of the above.
In the example of an AJ Russell BLE I restored, it exhibited the following:
Anson & Deeley's boxlock patent no. 1756 of 1875,
Anson's interceptor sear patent no. 4089 of 1882,
Deeley's ejectors patent no. 4289 of 1886,
and given a patent life of 14 years, unless you knew which patent is being dealt with, that could place the gun between 1875 and 1900, not hugely helpful!