Here’s how the system works:
Gun dealers are required to do background checks on potential buyers to make sure they’re not prohibited from owning a gun under federal or state law. In most states, those checks are handled by the FBI.
When it does a background check, the bureau gives one of three immediate answers: yes, no or delay. If a delay lasts longer than three business days, the dealer can choose to sell the gun without a definitive answer from the FBI.
Meanwhile, the bureau keeps researching the background check. If it later finds out that the potential buyer is barred from owning a gun, officials contact the dealer to see if it sold the weapon. If so, federal agents will retrieve it.
After 90 days, federal law requires the FBI to stop researching a background check and purge it from its systems, even without any final determination.