After additional thought, I think the source of my frustration is the OP's suggestions aren't really specific enough to do anything productive with ("we need to do something"), and I'm just trying to pin down those vague hopes into productive specifics. Initially off the list, are 'action' stories (i.e. demonstrations of the heroic use of firearms, more broadly), preachy tales (i.e. persuasive stories that are the express purpose of this discussion to a large degree), or vigilantism (even though a big part of the importance about civilian ownership/use is the fact that the 'system' fails us and cannot always be relied upon, a core tenant of the so-called vigilante theme). So the OP's initial suggestions close down most of the obvious avenues by which we might express pro-gun sentiment through media. Also a good portion of the perfectly legitimate arguments for civilian firearms (corrupt government/legal system, insurrection, military readiness)
Then the OP closes down non-emotional arguments involving facts/figures/reality as too confusing to people, as well as one-liner slogans that oversimplify the issue. There's just not much left, other than a few scant examples of films/documentaries that have nothing to do with firearms or self defense, and therefore will not translate very well (that is to say, they are not very useful examples, themselves). OP brought up the first post again, so I suppose I'll address it, again;
Two films I would suggest thinking about are "Thank you for Smoking" and the various "Left Behind" films. Thank you for Smoking does a fantastic job of making the people trying to control everything look ridiculous and successfully paints smoking as a personal choice that is no one else's business.
I guess it makes sense to demonstrate how illogical & counterproductive gun laws are in this country, but to do so requires a lot of technical and legal exposition that's even more off-putting than facts & figures. There very little technicality to smoking (and to the OP's credit about documentaries being unconvincing*, this film didn't exactly stop the anti-smoking brigade in their tracks, either) Heck, most pro-gun folks don't even understand the meaning or importance of Due Process, and fewer understand what is mechanically different about a semi-auto or machine gun. It's gonna be a rough road to both educate & then convince a bystander of anything on these topics. Movie about a guy with a SIG brace based on Kafka's The Trial, maybe? You see how esoteric and 'high concept' such an idea would be? Honestly, a scripted documentary about an AR 80% build party attended by a 'rainbow' of telegenic gun owners is probably the best you could hope for along those lines.
I think a drama about the negative impact of a successful self defense would bring a great deal of sympathy to firearms ownership as an embattled but "necessary evil".
Closest thing I've seen to a self-defense drama involving a justified shooter being rail-roaded by ambitious attorneys was an episode of Ghost in the Shell, but that involves both a police officer (quasi-military secret police of a corrupt state at that) and themes of vigilantism that muddy the message, and sci-fi setting that distracts from its relevance to reality. Pretty unique in that there is a lot of realistic questioning of the shooter's motives and
weapon, just as we'd expect from a George Zimmerman scenario. The emotional toll on the shooter is largely absent (he's a grizzled police vet) and the stakes are entirely 'legal,' and the villain & his attorney are the most cardboard of cartoon hoodlums, clearly deserving punishment. Yet in the end, even the 'righteous' stance of the victorious policeman is stained by his buddy seeking revenge on those from the corrupt DA's office.
But as a concept, it seems an appealing way to present our issues, if only because you've closed down all other approaches to the topic. The question, though, will it be entertaining? That I'm not so sure about, since the plot arc of a 'good shoot' is so different from most neat tales. You have the life/death struggle that is both the most emotionally intense, as well as having the greatest stakes,
at the very beginning of the story line, but a smaller-stakes moralist dilemma in the courtroom dominates thereafter; this is the exact opposite of what you want to hold an audience's attention. So you can either start the story after this in the courtroom, and use flashbacks to inform the viewer
Memento* style so as to 'sync up' its emotional impact with that in the court room, or leave those circumstances completely up to the viewer's imagination. Neither is very straightforward or easily digested, unfortunately, and flashbacks are a terrible way to tell a story since each is a break in continuity.
And you still have the hurdles of convincing the audience that;
-such an attack could realistically occur to them
-that they themselves could stop the attacker with a firearm
-that the consequences could involve a cruelly arbitrary or even hostile court proceeding (that mother in NJ that got pardoned by Christie was such a glaring example of real-world injustice as to be practically corny, and even then it took months to convince enough people that NJ was serious about putting her in jail that Christie could be convinced to pardon her; most folks kept expecting the DA/judge to dismiss)
-that mental & emotional after effects are real & healthy
-but are ultimately worth the chance to continue living, the responsibility of possessing firearms, and the cost of an attacker's life
The message is so complicated to address completely, that you almost need to show it in stark contrast to the alternative; maybe the story of a good man defending his family & abused by the legal system, who finally wins his freedom but with a felony rap/disarmament & is anti-climatically killed by an identical mugger on the way to work the next morning? Too preachy? Well, it happens to countless ex-cons in the ghetto every day who can't legally own firearms, as well as to the countless innocent people attacked by those very same men earlier in their lives. You want preachy, see
Philadelphia and
Uncle Tom's Cabin
TCB
*I would argue that
Philadelphia was so influential largely because attitudes toward AIDS were already softening in much of the populace, and it could act as a rallying cry, so to speak. Similar to how
Uncle Tom's Cabin didn't initiate the Slavery Abolition movement, but brought it to a full crescendo. Both were absolutely 'preaching to the choir' so to speak, but were entertaining/compelling enough more generally that the die-hards were willing to share them with the non-committal, who were then willing to hear an entertaining tale. As fun as
Unintended Consequences or
Atlas Shrugged are from a true-believer's perspective, neither are particularly well written, and therefore aren't the best vehicles for conversation (or conversion)