Freakonomics guy has some thoughts:

I never like the words “collect” and “data” when referring to trying to HELP us deal with the problem of criminals not obeying laws.  This guy doesn’t seem to be anti-gun nor overly pro gun so I’m sure he isn’t thinking about it from a “Shall not be infringed” standpoint… he’s a numbers guy and he wants numbers.

This is how it would go:

How many guns do you have in your home?

What are the serial numbers?  We at the National Firearms Safety Administration just want to see if there is a correlation between serial numbers and crime.

What calibers are your guns?  How much ammo do you have for each one of them?

Where do you store your guns?

Have you ever been so mad you for a split second wanted to use your gun?

Oh don’t mind me… just collecting some innocent data.  LOL