When it comes to the scientific test results in things like ballistic gel and whatnot, the measurable data puts the best of the best all within very minor margins.
So what we need to understand is simple, with handgun rounds, what stops the threat?
There are two ways to stop a threat - psychological and physical.
A psychological stop is when the criminal mentally gives up when they are physically capable of still fighting. Psychological stops usually happen at one of three points: when the gun is drawn, when the gun is fired, or when the criminal is hit just once, even if it isn’t a lethal or otherwise physically incapacitating shot.
With these three kinds of stops, the caliber matters little. These types of psychological stops are how .22lr derringers can incapacitate a criminal, even though a tire iron is very capable of dealing more damage than a .22lr through arm muscle. However, larger centerfire calibers (9mm/.40/.45) have a louder bang, so they have the edge up in scaring the criminal into submission.
The other type of stop is a physically incapacitating stop. This is when the criminal is shot to a point of physically not being able to keep fighting no matter how mentally motivated they are. This is a very hard thing to quantify because what incapacitates a tiny 90lbs sickly person vs a 250lbs very physically fit person vs an average 150lbs person who is hopped up on drugs is all very different.
There are different ways to physically incapacitate someone. The big ones are a “lights out” kill shot shutting down the brain, bone destruction preventing appendages from working, organ destruction, or bleeding out. Most incapacitations with handgun ammunition are through the last two - organ destruction and/or blood loss. Unfortunately, many criminals are still lethal threats while bleeding out or after their organs have been completely torn up. Sometimes bleeding out can happen very quickly, such as if an artery getting severed - people can go unconscious in seconds if one of those are hit. Even if there is a direct hit to the heart, a criminal can still keep shooting back for a few seconds. However, it is very possible to keep on living for hours after being “fatally” shot.
To further complicate things, what is determined to be physically incapacitating is different based on their weapon. For a rather extreme comparison, if someone is shot through the lower spine and paralyzed from the waist down unable to walk but their arms still work, they’re still very much a threat if they have a gun but aren’t much of a threat if they have a knife.
So what does this long analysis mean?
Shot placement is more important than bullet size or diameter. We must puncture something vital in order to physically incapacitate someone.
The bullet size and design simply increase the area of destruction the bullet creates as it enters in the body. So how can we get the maximum amount of area of destruction into a person? Well, if you do the math, 15 rounds of quality 9mm ammunition has a greater total area than 10 or 12 rounds of .40cal.
So when we look at the actual damage to the body, 9mm can actually give us greater amounts of damage to a person than .40cal or .45acp simply because we can put greater quantities of it on target.
But wait, there’s more!
There’s more to a gunfight than simply creating holes in a criminal, so the discussion of “which round is best” cannot start and end with how big the holes are in a criminal - especially since we know that where the bullet hits is more important than the size of the hole created by the bullet. When we talk about shot placement, this is where things turn into a case by case basis depending on the individual. So you need to know the answer to the question, “Which gun are you fastest and most accurate with?” I’d venture to bet that 99% of people with training will be the fastest and most accurate with a quality 9mm pistol.
Thanks to the FBI, we know in about 50% of all violent crime, there’s more than one attacker. So not only do we need to put holes in the right place on one person, we need to have the ability to do the same to other people as well. This is pretty easy to objectively quantify as the number of bullets in the gun determines the winner in this category. This depends on the gun, but you ger more 9mm in a gun than a similar sized .40cal or .45acp.
Speed of the engagement
Now every shooter needs to answer another case by case question - which gun and caliber allows you to quickly put multiple shots accurately on target on multiple targets? If you’ve never practiced quickly putting multiple shots on multiple targets, then you’re not adequately prepared for a self defense encounter and need to go train - preferably in a class, force on force class, shooting competition, or all three. (I better get back on target before I go too far down that rabit hole) Each shooter will perform differently, but like the previous shot placement section, I’d venture to bet that 99% of trained shooters will be fastest in this category with a quality 9mm handgun.
Make up shots
This brings us back to the capacity question. Gun fights are fast and brutal - but the vast majority of them in the civilian self defense world are over in seconds. Thanks to the FBI we know that the average hit rate of police officer and citizen is… not as good as we would want. Even in force on force training with simunitions in the hands of very skilled shooters, there are a lot of misses. It’s understandable due to the factors such as stress, moving targets, target identification, and the like. This means that we want as many rounds in our gun as possible to give us as many chances as possible to hit the target, let alone get an incapacitating hit on target.
When we consider the amount of physical damage capable by a full magazine of 9mm, .40cal, and .45acp, a full magazine of 9mm has the greatest capacity for destruction. It’s also pretty safe to say that average and trained shooters will be faster and more accurate with 9mm as opposed to .40cal or .45acp. Finally, when it comes to having the most number of chances to hit a threat and get an incapacitory hit on target on top of that, the more rounds in the gun, the better.
There is ONE caveat to what has been said. If you live in a state with 10 round magazine restrictions, then definitely consider .40 S&W. But aside from that…
All of this means that currently, 9mm is by far the winner.
Well, I guess this means I have next week’s blog post written for Locked Back… so I’ll just copy/paste this over there and clean it up a little bit… so that’s pretty neat for me.