[Ed. – It’s always so easy to propose to regulate other people.]
Why shouldn’t we require someone who wants to own more than two firearms, and who isn’t legally in the gun business, to file an application? Send some paperwork to the Bureau of Alcohol, Tobacco, Firearms, and Explosives; submit fingerprints and a photo; and send in a $200 fee along with the make, model, and number of additional weapons you’d like to purchase (and eventually their serial numbers). You would agree to undergo a thorough criminal, domestic violence, and mental health background check, knowing that if a permit to purchase additional firearms were granted, such a background check would be performed every six months (to ensure the applicant hadn’t fallen into a prohibited category of gun owner). Finally, and most important, the reason for requesting additional firearms would be stated on the application.
What would qualify as a legitimate reason? Maybe you own a huge ranch in Wyoming and need to supply your staff members with bolt-action rifles. Maybe you own a courier business that ferries valuables for clients and you need to arm your guards. As long as they’re all properly trained and vetted, and safe-storage precautions are taken, certain business exceptions like these probably make sense.