A Federal Firearms Operator's License
The more I think about it, the more I think this is the way to go.
It's not gun registration; I personally support that (knowing who has what gun seems like step one of training a militia), but it is politically beyond the pale today. But it is operator licensure.
It can possibly be divided into classes, a basic one for long guns, a more in depth check for handguns, and a very in depth check for NFA weapons.
This eliminates the gun show loophole. Any private seller can ask to see the buyer's FFOL. He can even check the serial number against an online revocation list. Before you give your son his first rifle, you take him to the ATF like you take him to the DMV before you give him a car.
In terms of passing this, I offer Federal pre-emption to the other side. I would also re open the NFA registry in return for some registration scheme. I really think with work this could pass, and would do some good.
TALKING POINT: "you have to prove you are eligible to vote, but nobody records what votes you cast. This is the same."
= new reply since forum marked as read
Because you just noticed gun cultists are losing, one state at a time?
The federal game is stalled, neutered. Federal preemption is a non-starter, as dead as any federal registration, because it would "dumb down" gun laws on balance.
I don't believe any sane person would bargain away advances just won, sorry. 
