Strong action on ghost threats?

Apparently the Biden administration is set to take action to crack down on "ghost guns".  For the uninitiated, "ghost guns" are guns without serial numbers, constructed from a receiver kit with a barrel and stock added, and it takes a fair amount of expertise and tools to construct one.  Since they're hard to track, the administration wants to classify the receiver as a gun (which it is not) and require background checks to sell them.

Lost in the debate is the question of exactly how many people are murdered using "ghost guns" each year, and the answer, according to Brady/Everytown for Gun Safety/Handgun Control Inc./whatever they're calling themselves now is "maybe 20 per year." 

If you really wanted to save lives and stop gun violence, what you'd do is work with states and cities to hire more homicide detectives and start solving murders, but apparently security theater is more the speed of President Biden.