I read through the NPR artical that 762x51 linked in his above post^^^^. A couple of things, a FFL is required by reg already to keep the bond books (records) for 20yrs, or until the business no longer exists, or the name changes, etc. If no longer in business, or name change or whatever, the bound books and 4473s are sent in to ATFE records. If ,as a licensee,you destroyed any records stiff penalties apply. I have held a FFL since 2001. I won't allow an unserialized (ghost) gun in my shop unless it's a pre-68 when serial numbers weren't required. I won't mess with a "ghost' at all. It would just not be a wise idea to have one in the shop. So, having a 'dealer' place a serial number on a 'ghost' in his inventory?!