I agree with the seminal thought that initiated this thread: the focus of forearm legislation should be on "regulating the militia". There's a good, readable, history of "the militia
" on Wikipedia. It's a good place to start.
Understanding the conception of the "organized" and "unorganized" militia, it would be conceptually easy to restrict possession of certain "arms, ammunition and military hardware" to the organized militia. Other, "non-martial" materiel could be allowed to the "unorganized" militia (i.e., everyone else), for sport, recreation, and personal protection uses - and for emergency use when called to service.
Note, I said "conceptually easy". Legislators are long out of practice in applying concepts to legislation. They tend to legislate based upon "notions" and lobbyist's creations. But reinvigorating the concept of "the militia" in the minds of the populace (and electorate) does a number of good things. People yearn to be "part of". Imagine the power of being "part of" the protection of society. "See something, say something" is exactly the kind of program that would be part of such an effort. Yes, it can be misused, but it is still "Civic engagement" - what used to be called, "good citizenship".
From there, when people feel invested in the process, they become involved. Given the cast of opinions in polling, good things can happen with an involved citizenry - like rational firearms laws, protection of the social safety net, etc.