Thanks Owen, that's where I would expect the old B.P. marks to be found. Some years ago Douglas McDougall produced three excellent books. The first two were in paperback '8 Bore Guns & Their Cartridges' and 'More 8 Bore Loads' then brought out a hardback edition combining the two. This was back in 1985 ISBN. 0 9506710 3 7 Very scarce now but worth it if you can source a copy. They contain much on reloading the Industrial type cartridges and all loads have been Proof House tested.

You still don't mention the Maker. I have a single 8 bore by T. Daintith of Warrington and a double by Joseph Lang. Great fun to use. Lagopus.....