In 1920 the powers that be, afraid of Bolshevik revolution, put all rifled cartridge arms on Firearm Certificates.
I suspect the fact that, when we did have a General Strike not a shot was fired,,owed nothing to the Firearms Act 1920. It was all very British.
The need for Firearm Certificates, the expense of the ammunition and the improvements in .22 Long Rifle -with Non-Rusting you could shoot a couple of rabbits for supper and not need to clean the rifle - killed the market for Rook Rifles.
Many were bored out to .410 as no certificates were needed for shotguns until 1968. Most of those also had the front part of the barrel turned down ahead of the fore-end.
This, along with the metal bored out to .410 threw the balance well back towards the butt. I find those where the barrel exterior was left untouched handle better as .410 shotguns.
