Background checks of private sales without gun registration will be universally ignored. Raise your hand if you have any intention of ever going to an FFL dealer and doing a background check to sell a gun to your buddy up the way. Thats what I thought. Thats the reason they have left private sales alone all this time.
If they set up a system where people could go online and determine if someone was a prohibited possessor, anonymously, many would do it.
Of course, the nanny state types would not allow that system, because it removes control from them.
The implied threat, of course, is that if your buddy is ever caught with an unregistered weapon he and you go to jail. C.W. II is coming if they keep pushing.
I was around when the 1968 GCA was debated. At the time it was widely recognized that records from a background check could morph into a National gun registration scheme, so, the following was added as an relief valve to prevent that:
"While current law mandates that a background check be performed if the seller has a federal firearms license, private parties living in the same state are not required to perform such checks under federal law. State laws however can prohibit such sales."
Beware of that last - it's a hooker.
Immediately after the Act went into effect, the liberals started the "loophole" B/S and have been pushing for it ever since. It is their wet dream to "expand" it.