The Infinite Wisdom of the American public has often pointed their fingers at legitimate firearms owners for "Mass Shootings" over the years; but recent information suggests that governmental agencies who are responsibility for updating the list of forbidden firearms purchasers have not been doing the job; the embedded article points right back to them.
"THEM" .. is the folks responsible for religiously maintaining current information on the Database which registers and tracks felons and madmen.
Report: FBI will add 400 million new records to NICS:
The Federal Bureau of Investigation will add more than 400 million new records to the database used to vet gun buyers, according to a report this week from the Trace. The National Data Exchange, aka N-DEx, contains incident and arrest reports, probation and parole documents, according to the report — a trove of information capable of preventing questionable gun transfers from proceeding, such as in the case of the Charleston church shooter.