THe Brady Act states that convicted felons who fail the NICS are REQUIRED to serve a MANDATORY 10 years in prison. That is not enforced. A law that is not enforced is worse than useless
Here in Florida a convicted felon who is caught with a gun goes to prison for 10 years. Mandatory. If they use a gun in a crime it's 10 years. Mandatory. If they fire a gun in a crime - 20 years mandatory. Shoot someone, it's 25 years up. Kill someone and they wll die in prison. Life without possiblity of parole.
Word gets around.