This one is pretty good
Note that in the UK, these are technically a section 5 firearm with a mandatory jail term for possession
I'd like to think you would just be told to destroy it there and then if caught with one, but don't fail the attitude test!
No, probably not a section 5 prohibited weapon (smooth bore, single shot, long enough barrel, not emitting a noxious gas or liquid - unless you use a can of
Coca-Cola), but almost certainly over the muzzle energy for a permitted airgun (12 ft-lb, 16.3J - so a muzzle velocity of 9.79 ms
-1 for a 340g can. My guesstimate from the video = 60 ms
-1). So you'd probably just need a standard firearms licence to possess one, possibly just a shotgun certificate (can't remember if the shotgun definition requires a mandatory choke and I'm too lazy to look it up) - I'd love to see the licensing sergeant's face if you submitted an application.