At first glance I’m not sure how they intend to enforce this. looks like it has some holes in it to me.
Since these are registered guns...
1. Send out a letter such as the one in the OP.
2. If the gun owner doesn't comply after a short time (say, a month), contact him again and explain that if he doesn't comply, he will be in violation of the law.
3. Shortly thereafter, show up at his doorstep (with a SWAT team as backup) and order him to turn over his property.
4. If he resists, kill him.
Exactly. Even if the new mayor wanted to “raid” some legal gunowners, what’s he gonna do, get warrants for every single registered rifle in the city? That’s assuming that you could even get a warrant based on a registration list.
So they’re going to go the “voluntary compliance” route, and see if they can get guys to barf on themselves.