The "yes, we can ban guns" assholes.
Like this one. Or
this frightening moron, who is advocating for a totalitarian police state.
Not going to happen, folks. Not now, not in the far foreseeable future. There is nothing about a gun that isn't replicatable, these days, with a set of decent shop tools. Making ammunition requires some knowledge of basic chemistry. Look, for example, at the Sten gun, a weapon designed mainly of sheet metal. Get a steel or even heavy brass rod or bar stock, drill it out, and you've got the barrel. If you're not worried about using it much beyond room-clearing ranges (or you don't care), it doesn't even have to be rifled.
Beyond that, the sheer quantity of guns in private hands means that tens of millions wouldn't be turned in. Americans are not like the Brits or the Aussies, passing a law does not mean people will obey it. If that were so, we'd be using the metric system today.
Didn't Prohibition, as well as the Futile War on Drugs have taught us anything?
The cops, from CBP and DEA (motto: "What Stinking Constitution?") down to the local po-po can't keep drugs off the streets. Over four decades of being able to track guns back to their original sellers and purchasers haven't done much to keep guns out of the hands of criminals. Using a gun in a violent crime is a Federal beef, but like a lot of other laws, that one rarely seems to be enforced.
But I digress.
Arguing for confiscation of all firearms will make it impossible for any negotiation. Why would the people on my side enter into discussions with someone whose bottom line is "we want it all"?
Then, how would it be possible? You'd need to change the Constitution. Which requires 3/4ths of the states to agree. If 13 states don't agree, an amendment is dead. You can probably name states that would never ratify such an amendment right off the top of your head. Even if you got over that hurdle, you'd have to send raiding parties into millions of homes and likely dig up millions of acres of land looking for stashed weaponry.
All that assumes, of course, that there would be no opposition to the confiscations. There would be. There would be on a multi-state level. And it takes no great leap of prognostication to foretell what would happen next.