A similar repoert that I got back concerning a Midland 12 bore made circa 1930 that split. I had sold the gun on more or less straight after proof. They came to the conclusion that it had had a slight blockage and been fired thereby weakening it at some point and then a subsequent shot did the real damage.
De-activation is very straight forward if you go down that route. The Proof House or a Gunsmith who does that work will advise the requirements. Just needs two slots cut down from breech end of the barrels (remover extractor first) along under the length of the forend. In a 12 bore the slots have to be 8mm. minimum width; don't know exactly what it is for a 20 hence contacting Proof House first. (5 minutes with an angle grinder). Two breech plugs welded in the chambers; I use threaded bar. Grind off the face of the breech. They say sufficient not to be able to support the head of a cartridge. (10 minutes with a decent drill bit and angle cutter). Nothing need show on the outside to indicate that the gun has been so treated and it looks like normal at first glance. It then needs sending to the Proof House for inspection. Best to have a person who does this thing have a look over it because if they fail it you have to pay and then carry out the extra work and re-submit which all adds to the cost. The Proof House de-act inspection certificate costs just over 20. I then take a photo copy of the de-act certificate and send that to the Police together with a letter outlining the fact that it is no longer a firearm and should be deleated from records as such. That's about it and then it can be sold on as a wall hanger to anyone who wants it. One like that would still be worth a couple of hundred pounds at least. Old pubs sometimes want them as decoration or someone who wants one for use in a play or film prop. I tend to do this quite often with old scrap worn out hammer guns that are beyond salvation rather than see them totally destroyed. Damn shame about that one though as such a lot of work went into it. Lagopus.....
