the NICS check currently declines aprox 40% of the applicants and of the 40% declined, most are declined for issues that are not valid and ulimately overturned. Those people can take months or years before clearing the errors. While it sounds good to think we are reducing the guns in the hands of bad guys the NICS check does not do that, it just makes the bag guys go somewhere else.
Personally, I experienced the failure of the system by being denyed access guns for nearly a year while I had to locate retired DAs and copsin a different state to prove that my "arrest" did not result in a conviction. My arrest was simply being picked up because I looked like someone else, When the error was found I was released (after 2 hours), no charges filed. That "arrest was not even on the books after 25 years but the NICS check found it.
Like most gun control laws the only people really affected negativly by them are honest people and not criminals.
I'm growing tired of feel-good legislation that only keeps the thinking impared happy.