For many years in the UK, a police license was required for possession of a rifle, but a shotgun could be legally owned by registering it by mail. In those years, many of those surplus rifles were converted to .410 shotguns and sold, not to hunters, but to those who wanted a piece of history but did not own hunting land, have a secure safe, and meet all the other requirements for owning a rifle.
(Today, I understand, even shotguns are under rigid controls, and of course handguns have been completely banned for Her Majesty's subjects.)