Simple - and serious - question - why is anything other than a handgun, shotgun or rifle needed?

[Posteritatis]

50. That'd apply to pistols as much as automatic rifles

Well, maybe a little less since hobby shooting with pistols is much more common - as other people have pointed out the worry about automatic rifles is a straw man, since even the US regulates those very, very strictly - but it's still close enough for the purposes of this conversation.

There doesn't have to be some specific, practical, visible application to want to collect something, and collecting it without any such applications in mind doesn't mean it's going to be used for criminal purposes. Some people collect weapons out of historical interest, or because they happen to like the aesthetics of one, or because they appreciate the design or craftsmanship in same.

I've actually been starting a sword collection in the last few months myself, on top of starting to make old-style armor. Both of those obviously have even fewer normal applications than a target pistol or the like - people fence with sport weapons, not actual rapiers, for instance - but I still enjoy the things out of my historical training, and I find the things kind of fascinating both as pieces of design and as pieces of art. This is despite the fact that, as with the scarier firearms out there, their sole purpose in being created is to harm other people. That doesn't mean I'm going to be using them to that end; I have my reasons for wanting a few, I know my own judgement, and rarely feel any particular need to have to justify either to others.