Look.
The common-sense key initiates would be authorised training and qualification, police checks, home security assessments including a recognised quality of gun safe, licensing and MANDATORY 3rd party risks insurance. An additional check could be a psycho-evaluation.
You can fix your definition of assault-rifle where you all fancy, and then ban 'em because they have no sports or utility value at all.
Where civilians are enrolled in to a State militia or part-time police service they would have a variation on their licences.
See? You can keep your guns and rights, but 85 gun deaths and goodness only knows how many injuries per day is a dreadful situation for everybody who cares, I guess.
Where I live anybody can own a shotgun or rifle, depending on the above........