We’ll be compelled to turn all weapons incrementally. First, whomever government decided is defective in some way, will be prevented from buying a gun. Defective to liberal government jackboots will be those who have criminal charges of any kind, like domestic abuse. Not convicted, charged.
Eventually, all but a very few will have to turn in their guns in order to do any banking, buy food, have a job and there will be a council that looks at your social media accounts to determine if you’re”racist”, homophobic, global warming denier, etc.
Nobody is going to go around collecting guns. People will give them up willingly, sadly.
Your scenario makes sense. It will be an incremental effort. Stopping it will require massive and sudden resistance. I'm not sure such resistance is possible ... but I'm preparing for it.