We all agree on the best handgun caliber, right? Hardly. Travis Pike adds fuel to the fire with this discussion of 9mm vs. 40 S&W.
The 9mm vs. 40 S&W debate has firmly replaced the 9mm vs. 45 ACP debate. It started when most law enforcement, including the FBI, began switching from 40 S&W back to 9mm. What happened? Why is the 9mm becoming the be-all, end-all cartridge for defensive applications? We have a better understanding of how firearms work, and more importantly, how bullets affect the human body.
For decades, the idea of stopping power existed. The idea was that a big projectile, moving rapidly, could hit a threat and shut them down within a shot or two. Stopping power pervaded the conversation but was never a solid science. For years people disliked the 9mm round due to a perceived lack of stopping power. The FBI even concluded in a report that “Handgun stopping power is simply a myth.” The famous 1986 Miami Shootout and subsequent findings cemented this idea in the eyes of the shooting public and led to the FBI Protocol that governs ballistic performance today.
Over time we discovered that stopping power didn’t provide an accurate assessment of handgun lethality. We discovered that projectile size was only important to a small degree. What was important was penetration, shot placement, and projectile expansion. A projectile needed to penetrate through 12 to 18 inches of 10% ballistic gel to reach the vital organs inside the body.
Projectile expansion caused by jacketed hollow points reduces the idea that a bigger bullet is better. Smaller rounds expand when they strike the body and grow in size. As they grow, they slow down but deal substantially more damage inside the body. Finally, we have shot placement, which ties to a shooter’s skills. You need to be able to direct rounds into an area where vital portions of the body exist, including the heart, lungs, and brain. When we talk 9mm vs. 40 S&W, which caliber excels in realistic lethality?
A modern 9mm round excels in the ballistic portion of handgun lethality. Modern jacketed hollow points expand and allow the 9mm round to grow in size substantially when it strikes a soft target. Most 9mm defensive loads penetrate within the 12 and 18 inch FBI standard. 40 S&W does the exact same and certainly meets the standards for an effective handgun round.
9mm excels as a defensive round for two reasons. First, it has remarkably less recoil than 40 S&W. This makes it easier to shoot and allows for faster follow-up shots. Additionally, 9mm uses a smaller bullet so firearms can carry more rounds. As you get into the realm of compact concealed carry firearms, these advantages become even more important. If you two rounds can both be effective, why choose one with higher recoil?
Also, it bears mentioning. 9mm is cheaper, therefore easier on the pocketbook when it comes to training.
Nothing is wrong with the 40 S&W. It’s just a bit outdated. More recoil means slower follow-up shots, but I won’t pretend that the 40 S&W is some magnum caliber that’s impossible to control. It’s a little snappy, and that’s it. If you have a 40 S&W and you like it, there is no big reason to run out and trade it for a 9mm. On the flip side, if I was shopping for my first firearm or for a new firearm, I wouldn’t choose a 40 S&W.
In the 9mm vs. 40 S&W debate, we also have to talk about weapon size. 40 S&W works best in compact and full-sized duty firearms.
Once you get into smaller firearms, that snappiness becomes much harder to control. Guns like the Glock 27 can be tough to handle effectively compared to a 9mm Glock 26.
The 40 S&W does offer a serious advantage when it comes to hard barrier penetration. That’s where that extra mass and velocity excels. It can punch through glass, wood, and the like and retain more energy than 9mm. It’s a rare situation where that might be an advantage, but it’s worth noting.
Caliber debates can always be a great way to waste time! It’s often a much ado about nothing scenario. Use the caliber you want, as long as it penetrates deep enough, expands enough, and it’s something you can control and shoot accurately. However, if you want maximum efficiency, then the clear winner in our 9mm vs. 40 S&W is 9mm.
Agree or disagree? Comment below.
Travis Pike is a former Marine Machine gunner who served with 2nd Bn 2nd Marines for 5 years. He deployed in 2009 to Afghanistan and again in 2011 with the 22nd MEU(SOC) during a record-setting 11 months at sea. Travis has trained with the Romanian Army, the Spanish Marines, the Emirate Marines, and the Afghan National Army.
He serves as an NRA-certified pistol instructor and pursues a variety of firearms-based hobbies.
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