Picked up a 12 ga 30 inch Clabrough & Johnstone, Makers, London & Birmingham sxs hammer gun, serial 3962, marked 2 3/4 on the fore-end lug. BP proofs after 1905.
Anyone tell me who actually built it, and approximate DOM??
Pictures below.





Dumb, but learning...Prof Em, BSc(ME), CAE (FYI)