Here’s the ONLY gun law that should ever exist:
Compel the Dept. of Justice to compile a list of all convicted felons who have not had their rights re-instated, and keep it current. Then provide a current copy of that list to all licensed firearms dealers – prohibiting them (under penalty of law) from knowingly selling guns or ammo to them. The only burden on the purchaser, would be to show ID - but only to the extent that his State government requires ID in order to vote. Walk in with cash - walk out with a gun - except for felons.
Thus, there really is no need for background-checks, forms, questionnaires, registration, or sales-records. This simple approach will be just as effective as all 22,000 current gun-laws - maybe more so.