Willfully is correct.
The upper gun is a short barreled shotgun. It is an NFA firearm, and registration tax is $200.
The lower gun never WAS a shotgun- never had a stock, never papered that way- it is a Smoothbore Pistol. (And yes, there is a paper trail to support that) Transfer tax is $5, as an AOW. It is ALSO an NFA weapon.
Neither gun may be transferred except by a dealer with the appropriate license.
If I were to take a regular Mossberg pump with an 18 inch barrel, shorten barrel to less than 18", and replace stock with a pistol grip, I did not MAKE an AOW, I made a SBS.
If I took a virgin Mossberg receiver that has never been assembled into a gun, and add a pistol grip and a short barrel, I have MADE an AOW.
If there is not a dealer involved in this, I would run as fast as I coulld to someplace that a lot of witnesses will see you were there, and not involved with that shotgun. Penalty for possession of either of the guns shown above- if not already registered with the BATFE is 10 years, no probation, no parole, and $10,000.
If there is a dealer involved, he will have the paperwork to get you started. You will also need to be fingerprinted, and have OK from your local Chief Law Enforcement person. Be prepared for a few months wait between sending in papers and getting approval. Oh- you must also be 21 yrs old. No NFA weapon can be transferred to anyone under 21.