There is no line of fire in a gunfight, that's the problem. People think there is, but there isn't. If you look at those old OK Corral type movies, the shooters are generally standing in one spot, facing each other, and even those are Hollywood fakery, not historic fact.
Those sharpshooters that they use in hostage situations, etc? Those are the best of the best, and they spend time lining up their shot.