Are there any states where the personal ownership of an armoured tank is allowed?
Yes, look up Jacques Littlefield on google, and there are others who own various WW2 tanks and armored vehicles with the weapons deactivated.
Does it even exist or is it (at least potentially) a case of anything goes?
Again the laws vary widely from state to state and community to community so it hard to say exactly where the cut off line is. Anything .50 calibre and under is classifed as "small arms" and is generally unrestricted.
State Laws
Federal Law
As for tank aramaments they would fall under the
Destructive Devices category and as such might be banned from civillian ownership in some states
edited again to add: Fully automatic weapons, or "Class 3" weapons, aside from being illegal in most states are really expensive because civillians are only allowed to own those that were in the US and registered with the ATF before May 19, 1986. So the supply is limited and the demand is high, just googling around for a little research I found a company in Texas selling AK-47s for $16k. The average person wont be (legally) owning one.
Edited by DrJones*, : added some links
Edited by DrJones*, : No reason given.
Edited by DrJones*, : No reason given.
soon I discovered that this rock thing was true
Jerry Lee Lewis was the devil
Jesus was an architect previous to his career as a prophet
All of a sudden i found myself in love with the world
And so there was only one thing I could do
Was ding a ding dang my dang along ling long - Jesus Built my Hotrod MinistryLive every week like it's Shark Week! - Tracey Jordan
Just a monkey in a long line of kings. - Matthew Good
If "elitist" just means "not the dumbest motherfucker in the room", I'll be an elitist! - Get Your War On
*not an actual doctor