Movies treat the cocking of a gun like an exclamation point. When Hardass McBadCop interrogates the lone surviving henchman, you can safely assume that, at some point, he’s going to make his gun go “clickety-clack” to let the poor schmuck know he means business. The sound of a clicking gun is so ominous that the MacManus brothers use it to close out their fruity little prayer in Boondock Saints:
That “click” is the sound of a hammer being cocked back, and movies seem to be saying, “This means the gun is ready to fire now, baby!” It doesn’t mean that, however. It doesn’t mean anything. The gun was already good to go.