Okay my internet went down for a while.
Let me take the replies in order.
1) Stopping Cho/ Virginia Tech. I don't believe that these laws would have stopped Cho. He would have just known not to go to a source that would do an NICS check. These laws will get a great deal of publicity, I can promise you BG's will take note.
2) The mass murder/spree killer/whatever BG isn't what these laws are supposed to stop. Okay, if you don't see the primary goal of these laws to target this specific type of BG who do you think they will stop? That's not a sarcastic question, if there are other uses for these laws, I might very well think they are a good idea. I'm very much open to that argument.
3) Stopping the flow into the Black Market. I really think that there is no effective way to do this. Even people in prison are still able get drugs and other contraband. I just don't think you can stop it short of a police state of some sort. Even then, think about the French Resistance or Warsaw Ghetto uprising in Nazi occupied territories. Besides, then we're just back to firearms aren't the only way to kill people.
4) An opportunity to catch them. I think that they will just get their weapons somewhere where they know the Police aren't looking. Inhuman determination makes them very good at staying under the radar.
Once again my questions and remarks are based on these most severe cases. If you are meaning something different who knows we might even agree.
Gaily bedight, A gallant knight In sunshine and in shadow, Had journeyed long, Singing a song, In search of El Dorado