My wife says I've ruined action movies for her. While I thought I was a movie buff, I found that she had seen movies the way I shot ammo in real volume. At her peak, she'd see 200-plus movies a year. Well, once we started going to movies together, and I taught her how to shoot, she began to see all the bad gun wrangling, gaffes, mistakes and improbabilities.
Remember the trick you learned back in grade school? Point at an object, both eyes open. Alternate opening and closing your eyes, and you'll find that only one eye/finger combination is actually on target. That's your dominant eye. Most people who are right-handed are right-eye dominant, and most people who are left-handed are left-eye dominant. Then there's that small percentage of people who are cross-eye dominant--meaning right-handed but left-eye dominant.
I was working with one cross-eye-dominant shooter some 20 years ago. Most shooters who are cross-eye dominant can learn to switch to the other eye. It takes work, but you reprogram your brain to accept the new primary eye over the old primary eye. She could not. Shoot a handgun, no problem. Pick up a rifle or shotgun, no chance. Her left eye stubbornly refused to cede the view to the right, and she'd be shooting feet to football fields to the left of the intended target. She had to have special shooting glasses made, ones where there was an etched blob in the field of view, directly where her left eye would see the sights. Only then, with no view available, would her left eye (or more correctly, her brain) cede the right of way to her right eye.
What does this have to do with action movies? First of all, most actors are absolutely horrible with firearms. It isn't their fault. The object of the exercise is to look good. To get the job, they have to have a skill set that is baffling look good, remember chunks of dialogue and project emotions not their own. Nothing about guns in that, is there?
The director is the one who determines what looks good and what does not. If you watch movies and TV action shows closely, you'll see that there seems to be an unusually high percentage of actors who are cross-eye dominant. They are right-handed but use their left eye to aim. (Except for one TV show where, in the opening credits, one of the actors is shown left-handed and right-eyed, even though the character played is right-handed. They must have flipped the film for "artistic" reasons.)
When the action shows were "pre-tactical," the police and investigators, the good guys and bad, the soldiers and Marines all fired handguns one-handed. It was easy to frame a shot (the photographic one) so the gun was in the frame and the actor's face clearly in view.
Fast-forward to today, where two-handed holds are in fashion, with the muzzle level, as the camera tracks the hero through the building. This hides the face--not much, but a bit, and when the face is hidden, it isn't the best angle.
However, if you have the actor cock his head as if he were cross-eye dominant, the camera frames the gun and the face, and the whole face at that. You're probably thinking, "That's wrong, and it doesn't change the appearance all that much, so why do it?"
Why, because it's more important on screen to look good than to do things correctly. Cinema is visual, and if you take a lot of little things and improve each of them just a little bit, you end up with something that looks spectacular instead of merely good. Cinematographers who do that win awards and make a lot of money. Those who can't get no awards and make a lot less money.