Here are the key pictures of Alan's gun,

This looks like a Greener pattern Martini without the Greener Safety lever.

These marks are on the bottom of the barrel The lower mark appears to be an Interim first proof mark from the London area.

These marks on the top of the barrel appear to conflict with the previous marks.By manipulating the colorI can just make out the center portion a crown over BR over 26 or 28 over a very faint broad arrow over WD. These appear to be Inspectors view marks from Birmingham Repair Section. Below that is an older almost polished off previous Inspectors view marks from Birmingham Repair Section.

At least that is my opinion based on my limited resources and experience. I used Skennertons Treatise on the Military Martini as reference for the Marks.

I would like to see a picture of the entire gun , then any marks on the iinternal part and the extractor.

Alan, does a 12 guage shotgun shell fit in that chamber?