We need to hear from a manufacturer, such as Jim Kelbly, who can give the straight dope on what paperwork is involved when a firearm is made.
My understanding is that new firearms are not licensed or registered. Paperwork is submitted that gives the serial number of the action or receiver but it is not necessarily shown as a rifle or pistol or shotgun. When Jim makes a new Cub action it is shown as an action since that is how he sells it. Someone taking that action and building a rifle is not required to submit any additional paperwork unless he is a licensed FFL and I'm not sure what his records would show. If an individual makes the rifle there is no paperwork whatsoever (except for any possible local requirements).
As far as I know, the only time a new firearm is registered is if it is one that requires it, such as a machine gun, short barreled rifle, etc. I made a couple of those back when it was legal to do so and I submitted a Form 1, along with a tax stamp, fingerprints, photograph, etc. Once registered, the firearm cannot be transferred or changed in any way without submitting an amended form. It can also be "unregistered" with proper paperwork and the receiver or action reverts to just that, a receiver or action.
I may be completely wrong on this stuff. BTW, that rifle that I sold last year started as an XP100 pistol, was converted to a rifle, then back to a pistol, and then back to a rifle. I know of other guys who did similar things back in the 20th century so if I'm guilty of breaking any laws I have a lot of company.
And another BTW. You guys always talk about how it's a waste of money to invest in something like a trued XP action because it will always be worth no more than the basic action. If that is so, how come I can never find a BR rifle built on an XP that doesn't cost as much as one built on a custom action?
Ray