Rather than seceding, if the Court rules the wrong way and says that the 2nd is a “collective” right, then the legislature there should declare each person between the ages of 16 and 80 to be members of the state militia, subject to annual call-up. They should be required to show up bearing their own personal M4, M16, M14 or M249 (all full auto weapons). When the governor signs the bill, you now would have a few hundred thousand people eligible to purchase brand-new full autos.
IOW, make Montana into Switzerland!