Illegal voters will still get through unless a PIN or SSN is required. NICS provides hits on prohibited persons (where state law is allowed to report information upstream).
If the system does not have any information on the person, they pass. All people passing must be purged from NICS within 72 hours.
Love the idea, but it reeks of the same (BS) impediment to voting that the liberals have stated all along: requiring a government issued voter ID is an onerous requirement that discriminates against poor people and folks in rural areas.
But somehow it's okay to inflict that same impediment on the rest of us.
Along with that, I think ICE agents at all voting locations would help deter some of the problems too. Just hand out ICE jackets to the polling agents and most of the problem would disappear.