As had been said, it’s a basketball term and I think was most often used when talking about the Lakers and other teams (but especially the Lakers) who ran a fadt break offense.
I first heard the phrase "Run and gun" as applied to photojournalism, and referred to things like police shootouts or serious fires or other spot news, situations where you plain don't have time to switch lenses or even take a meter reading. You got to the scene, rolled out and hoped to hell you had enough light and time to get the shot.
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