Two Smoking Barrels

Give a guy a gun, he thinks he's Superman. Give him two and he thinks he's God.

Police Superintendent Pang “Hard Boiled”

The image is iconic today.  One hero, two guns, ten-thousand bullet casings all falling at three-quarter speed.  They hit the floor and ring out in parallel with the fall of an army of bad guys carrying automatic weapons like wheat falling before a scythe.

John Woo is my shepherd, I shall fear no bullets

Simple.  Easy.  Impossible.

Wait, what was that last one?  Impossible?!  But, but, but—HOLLYWOOD!

Alright, fine.  It’s not “impossible”.  Let’s call it: so incredibly improbable as to stretch the bounds of reality to the point of breaking.  There are two key reasons why a trained profession wouldn’t go for the dual-wield when it comes to handguns: accuracy (biology) and stability (physics).

Two guns?!  It makes no sense!

Firing two guns, simultaneously, while likely the coolest thing you will ever do with both eyes open, also means you're not aiming either weapon.  Human vision, unlike that of say the chameleon, is binocular: our biology means we can’t see independently with each eye at the same time.  Even for a master shooter, sighting a firearm at a target requires aiming down the barrel which requires looking at that particular weapon and lining it up with the target.  You might be able to close your left eye, aim down the barrel of your right hand gun with your right eye and shoot then close your right eye, and aim and shoot on the left side . . . but why?  It’s not suddenly more effective to do this, which is why no military or police force in the world is training this way.

The other problem is that careful aiming at a target, even when you’re pressed for time, requires two

Because.  That's why.

hands to create a stable platform to fire the gun.  Gravity has a nasty habit of attracting objects, even if the Second Amendment is in full force.  This used to be the “teacup” hold, but that’s now considered an outdated and less effective method compared with the “straight-thumbs” hold.  Either way, the point is that it takes two hands on one gun to provide the stability for accurate shooting.  Because of things like “physics”, all guns have a recoil or kick.  This will cause the gun to give a little (or big) jump when you start pulling the trigger.  Having a proper grip on the gun, meaning two hands, will allow you to keep firing it accurately and effectively to mow down more bad guys.

Pew-pew!

That’s not at all the kind of thing Hollywood has in mind when Tom Cruise or Scarlett Johannsson are on the screen.  If our heroes need two guns in their mitts, then biology and physics be damned!  Tom is going to be two or three times more effective at taking out bad guys, and Scarlett . . . well, she can have whatever she wants, now, can’t she?  For the rest of us mortals, the only time to pull two guns is if you have no other options and just want to put a lot of lead into the air as a deterrent.  This is called “spray and pray” and you have a better chance with an automatic firearm and belt-fed ammunition than you would a semi-automatic handgun with a much smaller magazine.  Nine or even fifteen rounds goes really quickly when you aren’t picking your targets, sighting your weapon and squeezing off a round.