IMO, it's over people. If this passes, they will require people to register all their weapons with ATF so they can track them. Any reason they want will trigger a visit from jack booted thugs. Your wife leaves you and you get a script for Vallium and you lose your right to have guns.
If they don't require you to register your guns, what good is it? If I have 30 guns, I could buy and sell a hundred guns and they know NOTHING unless they require me to register them. If background check was just to check my name in a database, then I'm sure no one would care. They will never settle for that though. ATF has been copying FFL forms for years since Waco. They even raised the FFL licence cost to get casual gun enthusiasts out of the gun business. My brother in law had his licence to buy and sell for himself and family and friends. He charged nothing or very little because he didn't use it as a business. When the price went up, he gave it up. The BATF came to his home and took his books. Even Dan Rather on CBS News admitted that they were entering the data in a huge database even though it was illegal. To think you have a gun no one knows about is a pipe dream. If they come looking for it, you better produce it or the waterboarding will begin. Thus has it always been in every fascist country since the beginning of time.
I know! Where is the due process? What happened to a court adjudicated finding with the right to counsel to contest the shrink's findings?
The other tactic that comes to mind is not to push the registration component. Just require the background check.
Then set up stings. Most people making a private transaction won’t comply. They they get arrested for a felony and lose everything.