Adding to what Bruce has posted, these are permitted in the USA but fall under the "short barrel rifle" definition
according to ATF so require Class III papers with the same finger print cards, background check and $200 tax that applies for owning a machine gun. Basically if you can vote in the USA, you can legally own one once registered but you are a Felon waiting to be arrested if you start work cutting down a rifle prior to receiving your papers with tax stamp affixed.
Took four months to get a ruling on what they would classify the device since it could be seen as a pistol, mortar or short barreled rifle depending on how you looked at it. Then the applications could be filled out and submitted.
Took several more months to get them to sign off on it but that is due to their agency being overwhelmed by people doing modern firearms registrations since Mr. ’O took office and stirred up the gun community.
