The FBI can only operate within the law, and although common sense would have said a severely mentally ill person shouldn't own a gun, the law says differently.

Every time anybody tries to make common sense changes to gun laws that would make it harder for seriously mentally ill people and criminals to own or get their hands on a gun, the NRA and gun nutters vehemently oppose any of those changes and therefore nothing changes.

Don't blame law enforcement when they're not given the tools they need to to have any effect on the gun violence epidemic in this country, speak up and demand common sense gun regulations, or regurgitate NRA talking points and see nothing change.