So no limits at all - no limits on ownership, no limits on access to said weapon, no weapon safety skills courses? Just buy, own and use anything you want, any time or anywhere you want?
Don't forget, that part right there implies someone actually has to work, and probably quite a bit, to obtain whatever it is they want. A simple pistol will cost them ~$300, a rifle probably $1k to $3k, and a nuke probably $8mil. They will likely have a damn good reason for whatever they are buying if it's expensive enough.
(I can't see a random unstable nutcase coming up with $8mil for a nuke. It's even hard to imagine someone like that coming up with $1,000 for a machine gun.