The Tiahrt Amendment was passed in 2003 and has effectively blocked all state and local investigations of illegal gun market because crime trace data can not be shared between jurisdictions and the information that ATF provides to local law enforcement must now only pertain to the particular crime investigation for which that gun was used.
It also requires the FBI to destroy certain background check records within 24 hours making it impossible to correct mistakes.
One of the favorite slogans of the NRA is "we don't need new laws, we should enforce the laws already on the books." The NRA can feel safe with this statement as the Tiahrt Amendment (the wording of which was approved by the NRA prior to its passing) prevents the enforcement of the laws already on the books.