Federal legislation. Article I and the 14th Amendment both give Congress adequate authority...and the Voting Right Act sets precedent. Specifically: Congress passes a law stating that certain specified states (CA, HI, MD, NY, NJ, MA, RI, CT, and IL), owing to their unsatisfactory record, are no longer permitted to regulate firearms, accessories, etc, without preapproval from the Federal courts. All existing laws are void, all laws are presumed unconstitutional until proven otherwise using strict scrutiny. We're winning at the national level. It's time to use that strength.