Alphecca

I'll happily disclose the other parts of the film, so long as no one accidentally reads the:

SPOILERS AHEAD.

When Cruise flees his home with his children, he makes a point of bringing his revolver.

Then, we don't hear anything about it until the pier scene. Here, Cruise's son forgets to avoid large crowds, because their family has a rare working car and everyone else wants it. So the mob starts tearing the car to pieces to get ahold of it. And just as Dakota Fanning is about to be crushed under a pile of frantic adults, Cruise fires off several warning shots, stopping the mayhem cold.

Then, another civilian sticks a Sig in his ear and demands the car. Cruise drops his gun, and asks to merely retrieve his daughter. The Sig guy allows this, Dakota is fetched, and Sig guy gets in the car.

Then, the real Brady Bunch shot occurs when another random guy picks up Cruise's weapon with a crazy look in his eyes.

Then, as Cruise and family sit in an abandoned diner to cool off, we see the guy who picked up Cruise's weapon shoot the new owner of the car, though it's clear that even he won't be able to hold it for long.

So, the gun saved his daughter from the mob, but it also inspired another guy to commit murder. I'd say it's negative with slight ambivalence.

(later, however, the film makes a stirring argument for civilian possession of hand grenades. Also, Tim Robbins' character has a 12 gauge, not a rifle.)

WORST. ENDING. EVER

another civilian sticks a Sig in his ear and demands the car. Cruise drops his gun, and asks to merely retrieve his flag daughter. The Sig guy allows this, Dakota is fetched, and Sig guy gets in the car.