There isn't legislation anywhere, where high gun crimes were not the reason for instituting them in the first place. You are suggesting legislation came first, which caused criminals to start shooting everyone. The opposite happened.
The safest place in America, is the outdoors in western United States during deer season. Everybody is packing a firearm. Everybody smiles and waves at strangers when you pass on the dirt road. You can leave your campsite unattended all day long and everything is still right where you left it when you come back at the end of the day. 100% firearms strapping populous. 0% crime, let alone murder.
Yeah! It would be as insane as Trump declaring a National emergency to build a Wall! Thaf would set a dangerous precedent of "Hey, if he did it to get what he wants, why not us?" but lucky such a thing... won't... happen...
Even if that happened, they would NEVER take everyones guns away. Knee jerk reaction for simpletons to keep them voting Republican. Never, never, never, will we ever take American guns away and for a few reasons. 1. Complete revolt by at least 20% of the people. Numbers too high for any politician to stomach. 2. As a numbers game, it's impossible with the shear volume of guns out there. 3. It would require a change in the Constitution and there is no hope in that.
Imagine military type vehicles driving slowly down every street, ransacking every house in America, looking for and confiscating every weapon, loading them up like cord wood, to be melted down and destroyed. All 393 million of them. It would require the entire military and all its vehicles, martial law and people being shot in the streets.
That scenario is more Mad Max than Mad Max. It is NEVER going to happen.