Another thought on Spring City, the Utah city of close to 1,000 residents that is considered requiring every household in town to have a gun, and is still considering requesting that each household own a gun.
I heard Mark Shurtleff, former Utah attorney general, say mandating it would have been illegal. Thought of the law that would make it illegal (having been looking at state laws a week or two ago), and looked it up. It's 53-5a-102-4, "All authority to regulate firearms is reserved to the state except where the Legislature specifically delegates responsibility to local authorities or state entities."
Is asking the city's asking residents to own a gun in any way a form of regulation? Don't know. Guess as long as you are not making gun ownership a requirement, it isn't regulation.