[Kochman]

It is possible that a felon would be stupid enough to attempt a purchase with a 4473 check, and that the purchase would be frustrated when the check comes back negative.

Do you understand that this does not keep the felon from getting a gun?

As I previously cited here, it does.
Between 2002-2003, over 120k people were denied firearms due to 4473.
That kept them from getting the gun from FFLs.
If we expanded that to all stranger-stranger transfers, it would prevent all but family and black market acquisitions.

That criminal's possession of a firearm is already illegal. Do you really think that making it extra super double illegal helps?

Absolutely, because it makes it extra super double more expensive, at a minimum, and is yet another charge you can throw at them during the commission of a crime if they use their illegal gun...
Charges - Crime, illegal possession of firearm, illegal purchase of firearm (instead of, ooops, he bought it at a gun show)

There are very few things I can guarantee, but I believe I can guarantee this: somewhere at some point in the future someone will be wrongly killed with a legally purchased firearm, and there is nothing you can propose which will prevent that.

And why does this mean we shouldn't use a 4473?
I've documented that it has stopped a lot of potential crimes (of that 120k, you can't honestly tell me that nothing was prevented).

@ATW

Why not keep checks voluntary, but impose criminal penalties for people who transfer them to prohibited persons if they choose to forego the check?

That's de facto the same... because people will not always use the form even if it is law. However, it will punish the irresponsible, which is the same thing you recommend. I support that.