The problem started way before The NICS Improvement Act became law. i'm a veterans advocate and i can tell you that the VA has been reporting veterans with fiduciaries to NICS going back to The Clinton era.
The VA has long had a procedure to report veterans with fiduciaries to NICS. The same is not true of the social security administration. The Obama administration attempted to extend the VA procedure to social security recipients with fiduciaries and got slapped down by congress.
At a meeting i attended our former US senator from OK Tom Coburn solemnly promised veterans he would eliminate the reporting of veterans to NICS. Coburn lied like a dirty dog, kowtowed to Chuck Schumer and did a net nothing for veterans.
BTW: When General Shinseki was VA head he refused to report veterans to NICS. The guy Obama hired to replace Shinseki began reporting veterans with fiduciaries to NICS.