Here in UK you'd have to be pretty serious about wanting to shoot any of the small and unusual stuff you've seen on this thread that are still shootable.
The problem is that owning an antique is the easy bit, it's the shooting of it that can pose a problem.
See, unless you are a full member of a gun club, you can't have a Firearms Certificate that authorises you to shoot such a gun - they are ALL treated exactly the same way as if you were shooting any modern firearm in any calibre - like a Accuracy International in .338 Lapua Magnum.
Same with ANY replica - any and ALL firing replicas are treated as same as any modern firearm.
As you might imagine, all this tends to crimp your enthusiasm somewhat.
Firing one when nobody is looking, and getting found out and snitched on by some 'well-meaning' person, puts you in a competition where the top winner can earn a five-year-long vacation, with food and clothing, in one of Her Majesty's big grey hotels.
tac