400 - from the list of proof marks in the Blue Book, the gun dates from 1868, but it is indicated that that mark was used into the twentieth century (no help). Is there a more comprehensive list of marks available?
Ithaca:
When you say "that mark was used into the twentieth century (no help)", it's clear that you're not understanding the marks. British proof is never just one mark. There are multiple marks, and they're used as a SYSTEM. The marks used 1868 to 1875 differ from those used 1875-1887, and so forth. Each system of marks introduced with each new revision of the rules of proof - 1868, 1875, 1887, 1896, 1904, etc. - is unique. We need a description of each mark present, and the order they're in. That's why photos would be best. Yes, some INDIVIDUAL marks in the system of marks continued in use through multiple revisions. For example, Birmingham's Definitive proof mark (crossed sceptres with a crown in the upper angle and the letters "B P C" in the other three angles) and inspector's "View" mark (crossed sceptres with a crown in the upper angle and a "V" in the lower angle) were in use from 1813 to 1904. It's the OTHER marks that accompany the Definitive proof and view marks in the system of marks that changed and make the system of marks for each revision unique.
I've never paid any attention to the blue book so have no idea if it's coverage of British proof is reliable or not. I would bet not. Most of the reference works that contain coverage of British proof are poor, and many contain multiple errors. The most accurate coverage for British shotgun proof marks I've found is in Part IV of Nigel Brown's "British Gunmakers - Volume II".
