> Which makes the kind of regulations they _want_ around firearms (i.e., regulate/tax them out of existence) kind of tricky.

Not really. They do whatever regulations they want all the time. It's just sometimes federal government steps in and forces certain local laws to not be enforced.

I was able to get CCW permit in LA only due to such intervention.

There also exists a pesky fourth amendment that should protect people from laws like this but unfortunately it doesn't have the industry and lobbing that the second amendment has.

The 28th amendment: right to keep and bare 3D printers