umgud wrote: “BTW, if there is no registration, why the hell do they need a serial # to conduct a background check on the buyer?”
A record is maintained by the licensed seller. The name of the purchaser must be erased from the data base after IIRC three days but the serial number is retained and liked to the licensee. If ATF finds a firearm at a crime scene, it can ask the licensee the name of the original purchaser.
Big stink several years ago about the ATF maintaining names linked to serial numbers illegally.
That’s why I purchase a firearm and then check the obits for the next three weeks. You can figure the rest out.