I figure many of us won't have to worry about them coming to the door.
If they start in some of the gang-infested areas of LA or other big cities, there won't be enough left of the "authorities" to do many more door-to-door campaigns.
They'll just declare them illegal and then pass other laws mandating the reporting of any sales of "supporting products" -- ammo, reloading gear, lead, powder, holsters, etc. -- so they can raid a home based on "probable cause".
They can afford to wait. Wait until you use any kind of firearm, like a shotgun, in lawful self defense. Then, they'll search your house thoroghly and if they find a hidden handgun, you go to jail for possession AND committing a homicide with an evil handgun present.
Know anyone with access to a high-temperature smelter? Take a couple of least-valued guns, strip the action parts out of them and have the frames, barrels and slide melted down into high-quality steel ingots or barrel blanks for rifles. When the authorities come, show them the blanks or ingots and say "I had them melted down into barrel blanks so I can build my custom .222 varminter rifle".
Once melted down, they're no longer "firearms". Of course, the
good guns are safely hidden somewhere.