I’m pretty sure it is a uniform federal law. Anytime you fill out the 4473 form at a dealer they contact the ATF hotline and provide the customer info. ATF will inform the dealer proceed, decline or delay the transaction.
In CA we have the background check, frontground check and sidegrounds and 10 day waiting period on all guns. But you can drive a few hrs to Nevada and get all the weapons you want when you handover the cash.