This may be because the blood on the streets is already there.
Homicides by gun are more than all other methods of killing someone combined in the US and has been for a long time. Only three countries in the world have more homicides by gun than the US does (cite).
Gun control only works if there is meaningful control. To date most restrictions have had loopholes big enough to drive an ocean liner through.
Yes it is enshrined in the Constitution but my opinion is Heller was decided wrongly…stunningly so frankly. Yes no one asked me, yes Heller/McDonald now inform current US law. Nevertheless I think there is an absolutely acceptable reading of the Constitution that permits far greater restriction. Afterall they already do that. “Arms” could mean any weapon by definition. The SCOTUS already allows arbitrary lines to be drawn on what weapons are permissible for the average Joe to own. So, you can stay within Constitutional boundaries and not toss it wholesale and achieve gun restrictions.