manta, you're just not getting it.
The existing background check law is a farce. Depending on who you listen to, untold thousands of people were denied the purchase of a firearm because they didn't pass the background check. They either:
1) lied on the submitted form, which is a felony, and only a scant few were prosecuted. So the existing law isn't being enforced. ; or
2) the information in the NICS system is flawed, and untold thousands were unjustly denied the purchase of a firearm.
Thirdly, people who know they won't pass a background check won't submit to one and will buy one illegally on the black market, or use something else to do their dirty deed.
So logic only tells you that piling any new laws on top of one that isn't enforced, or more people submitting to a flawed system, accomplishes nothing. Nada. Zip.