It started with the arbitrary denial of 2nd Amendment rights to all convicted of a crime, even where a gun played no part in the crime.
FReepers generally love this rule, but it remains the wedge by which all the other loss of their 2nd Amendment liberties stems, and that includes background checks, waiting times, restricted purchases, ammo registration and all the rest. Ownership restrictions are like being just a little bit pregnant -- sooner or later you have to face the full facts about what you've done.
I do not hold that the state can no more take away your ability to self defend than it can your first amendment right to speak.