[chias]

They all have serial numbers, and you had to show ID when buying them. So yes they are registered, you just might not be aware of this fact.

[douche]

At least in the US, private sales are legal, and there is no requirement to file any paperwork whatsoever.

Moreover, there is a staggering number of firearms that predate any sort of government record-keeping. It's not like these are muskets and black-powder revolvers, either - most of the designs for hunting rifles and shotguns are nearly unchanged from models that were available a century ago.

[15155]

A paper 4473 sitting in the store-room of my local gun dealer (of which, there are thousands) is hardly akin to registration.

All firearms I have purchased privately, been gifted, or manufactured also do not fall under this category.

[RyJones]

I cut a bunch of them from aluminum, for which I showed no ID, and they do not have serial numbers.

[scintill76]

OK, nice. So, my analogy does not apply to all cases, but the point is that many guns are tied to government ID, as are many internet connections. Subverting that is of course possible, and an alternate solution to those problems.