This is my first thread after being fascinated with reading here for some time now. I’m hoping some of you may be able to offer some wise counsel on an Army Navy CSL shotgun of mine. It’s a 12 gauge side by side box lock extractor which I believe to be fairly early. Glascow has no records on the guard number, and it is NOT nitro proofed. What does not seem to fit though is that the barrels do not appear to be Damascus, and the proof marks seem as if it has perhaps been proofed at different- though both early- times.

Is it possible that a sxs box lock extractor might have been made with fluid steel barrels in the late 1880s?

Welcome. Steel barrels were being made in that time frame. Guns proofed before 1896 were not marked for Nitro. Guns can still be proofed for Black if the owner request it but generally they will be proofed for Nitro. NP see below. From hallowellco.com

Welcome to the Forum Ploughjogger.

It will help if you are able to post photographs of the object of your enquiry.

I use a site called Imgur, which is free and reasonably easy to sign into and use.

Mine has the London proof marks from 1868-1875, but then also has the 12c in diamond and choke mark of a later proof.

https://i.imgur.com/YLwoEDU.jpg

Each barrel also marked with a capital A and also this mark:

https://i.imgur.com/dUpPF3w.jp

I have no information regarding the barrels of A&N CSL, but P. Webley & Son began using Siemens steel barrels about 1880 and reported excellent results.

Shooting, Thomas de Grey Walsingham, Ralph Payne-Gallwey, Gerald Lascelles, Archibald John Stuart-Wortley, Simon Fraser Lovat, Charles Lennox Kerr, 1886
http://books.google.com/books?id=MT9NF4BnAFIC
‘Siemens’ steel barrels are fairly good and very trustworthy for cheap weapons...

The 1891 Birmingham Proof House report listed several other domestic steel barrels
https://docs.google.com/document/d/1cvqRzkg0wEjhAAcFWr8gFi7aPFRsSIJ_hahfDxmrNAU/edit

Also be aware that Damascus barrels are often blued or Blacked as they call it.

I had an Army Navy boxlock with fluid steel BP proofed barrels that dated to about 1890. So quite possible.

It appears that the proofmarks are from the 1887-1896 period. We cannot see if it is marked CHOKE. It may have been made without choke.

One barrel is one is not

For OP