Consider this, in relation to the current "ghost gun" hype...
(and for this discussion, lets consider a "ghost gun" a firearm made/assembled at home, by a private citizen who does not have a Federal License to make or to sell firearms)
1) for nearly a century Federal law has allowed the individual to create a firearm themselves, at home, for their own personal use, with no license or registration requirements. NONE. THAT IS THE LAW, and has been for a loooong time.
2) The person who made that gun at home (today being called a ghost gun) has always been allowed to sell it or trade it, or give it away, when they got tired of it. This is also part of the long existing law. WHEN the maker does that, the "ghost gun" is required to have a serial # put on it, and registered with the Federal govt the same way all gunmakers are required to do. Again, part of the long existing law.
Home "manufacturers" are NOT allowed to make their guns for sale. Doing that requires Fed licenses for manufacture, and for being engaged in the business of dealing in firearms. YET AGAIN, something covered in existing law.
Understand this, the guy who builds a dozen AR variants at home, unregistered, for his own personal use IS complying with the law. If he sells one or two or even all of them months or years later, he is complying with the law, PROVIDED that at the time of sale those guns meet the same requirements as commercially produced firearms (ser# and registration with the Fed,etc.) If he does not do that, then he is an illegal firearms manufacturer and trafficker, breaking several existing Federal laws.
Now, on to the big talking point about ghost guns, their being "untraceable".
This is BS. Or, more properly it a PARTIAL TRUTH.
First point, in order to trace any gun, the police (ATF etc.) have to have it. That means they have to have it in their hands, having recovered it from a crime scene, or taking it from a suspect, etc.
That means they know where they got it, and why. That's step one. After that, they want to know where it came from, and how it got to where they got it. And that's the rub. Regular, legal guns will (since 1968) have a serial # that the cops can trace from the manufacturer to some point of sale. They can do this by looking at records. They may not even have to get out of their chair to do it. They may be able to trace it from the maker to a jobber, to an FFL dealer right from their computer desk, and then have to go to the FFL's location and look at their paper records (dealer bound book, and 4473 forms) to find who purchased it.
After that, it becomes a matter of field investigation. Ghost guns with no serial# are NOT "untraceable". What they are is "not as easily traceable" as regular ones, essentially requiring the trace to be all field investigation.
Not intending to bash anyone, but what this means is that to trace a ghost gun, cops have to get off their butts and do the difficult investigative work to find the answers, instead of just being able to look up records.
they have the gun in question, they know who they took if from, and why. They can find out where that person got it, but it takes work, and time, and isn't easy. They may have to trace it through many people, without a paper trail to guide them, to find its actual origin. Difficult, and in some cases, no doubt they will not be successful, but as a general thing, not impossible.
They can trace illegal drugs back to their suppliers, I see no reason they can't do that with illegal guns.
Complicating the matter is the value of knowing where the gun originated and how it got to the person it was taken from, vs. the amount of time and police resources required to actually do it.