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When it comes to pistol cartridge debates, shooters have been arguing about the 9mm vs the 40 S&W for 35 years. What got the argument kicked off was an infamous FBI shootout in Miami, in 1986, when FBI agent Jerry Dove shot Michael Lee Platt with a 9mm pistol. The 115-grain Winchester Silvertip bullet stopped short of Platt’s heart, and he continued to fight. Ultimately, two FBI agents were killed and five were wounded, and the supposed failure of one 9mm bullet spawned the FBI’s rigorous ammunition testing protocol, which ultimately led to the creation of the 40 S&W cartridge and its adoption by the FBI.
That’s the foundation of the debate. But is the 40 S&W really better than the 9mm? And if so, why did the FBI switch back to the 9mm? Let’s settle all this with a full breakdown of the 9mm vs 40 S&W question.
9mm vs 40 S&W: Table of Contents
9mm Luger Overview
40 S&W Overview
9mm vs 40 S&W: Capacity Comparison
9mm vs 40 S&W: Terminal Performance
9mm vs 40 S&W: Recoil/Shootability
9mm vs 40 S&W: Best Loads
And the Winner is
The 9mm Luger Overview
When the 40 S&W was introduced in 1990, the 9mm Luger cartridge was almost a century old. During those 90 years it had become very popular with law enforcement and civilians, but there’d been a long standing debate whether fast and light 9mm bullets were better than slow and heavy bullets fired by the 45 Auto. After the Miami shootout, 45 Auto lovers said, “I told you so.” But with the introduction of the 40 Smith & Wesson in 1990, the 9mm vs 40 S&W argument erupted and has raged on.
The ammunition developments that resulted from that shootout soon elevated 9mm performance. Bullet engineers learned how to leverage the high muzzle and rotational velocity of bullets fired from a 9mm pistol to enhance terminal performance. By 2015, the focus had shifted to shootability, and the FBI realized their agents shot 9mm pistols better than 40 S&W pistols. So, they reverted back to the 9mm and the improved ammunition for it. As the FBI goes, so too does most everyone else, and today the 9mm Luger is the most popular pistol cartridge in America and worldwide.
40 Smith & Wesson Overview
After the Miami shootout, extensive FBI testing resulted in their adoption of 10mm pistols for general service. The 10mm ammunition they chose was a downloaded 180-grain bullet at about 950 fps. Many agents felt the issued S&W Model 1076 pistol in 10mm was too big and heavy, and as a result, the FBI switched to the 40 Smith & Wesson in 1997. When the FBI made the switch, soon most every law-enforcement agency in America did too. Suddenly, the 40 S&W was everywhere.
Civilians bought 40 S&W pistols too, partly because the 40 S&W bridged the gap between the 9mm and the 45 Auto, but also because of the 1994 Federal Assault Weapons Ban that limited semi-automatic pistol magazines to 10 rounds. Because the 40 would work in 9mm-sized handguns, the ban took away the 9mm Luger’s higher-capacity advantage. From its introduction until 2015, the 40 S&W was one of the most popular pistol cartridges available. Then, almost overnight, it seemed to crawl under a rock and die.
9mm vs 40 S&W: Capacity Comparison
When comparing guns of the same size, like a Glock 19 and a Glock 22, the 9mm pistol will hold 26 percent more ammunition compared to the 40 S&W. But how much does capacity matter? Statistics show that in most civilian self-defense encounters where a handgun is used, it rarely matters at all. However, in a law enforcement, capacity can be a big deal. Not just in terms of the amount of ammo the gun’s magazine can hold, but also in the amount of ammo an officer can carry. Three Glock 19 magazines hold 57 rounds of 9mm, while three Glock 22 magazines hold only 45 rounds of 40 S&W. Also, with the expiration of the 1994 Crime Bill, the 10-round magazine restriction is no longer a thing. Up until then, 10 rounds of 40 S&W seemed better than 10 rounds of 9mm Luger. But the smaller diameter Luger cartridge has now regained its capacity edge—except in some states that limit magazine capacity—and a lot of shooters like the idea of a pistol that holds more ammunition.
Winner: 9mm Luger
9mm vs 40 S&W: Terminal Performance
Semi-auto pistol cartridges simply do not have the velocity to substantially damage tissue beyond the diameter of the hole the deformed bullet makes. To see that type of damage, bullets need to impact at substantially faster velocities. Because of this, the frontal diameter of the upset bullet matters. When bullets of the same type are compared, 0.40-caliber (10mm) bullets tend to upset with a wider frontal diameter than 9mm (0.355-caliber) bullets. Of course, the larger the frontal diameter of the deformed bullet, the harder it is for the bullet to penetrate.
Still, today’s ballisticians craft defensive handgun ammunition—regardless of caliber and cartridge—to perform well in the FBI’s testing protocol, which stipulates penetration of between 12 and 18 inches. This means that the terminal performance of good 9mm Luger and 40 S&W ammunition will be very similar, but in most cases 40 S&W loads will create a crush cavity that’s 10 to 20 percent larger in volume. On the other hand, some 9mm loads outperform 40 S&W loads when encountering the intermediate barriers that the FBI includes in their testing. Here’s a breakdown of some 9mm vs 40 S&W loads in terms of terminal performance:
Winner: The 40 S&W, by a hair.
9mm vs 40 S&W: Recoil/Shootability
The shootability of 9mm pistols was one of the major considerations that led the FBI to return to it as an issue sidearm. Recoil complicates shooting no matter your experience level. Depending on the loads compared, the 40 Smith & Wesson will recoil with between 10 and 40 percent more force than the 9mm Luger. I’ve conducted a lot of testing to determine how recoil impacts pistol shootability, and I’ve discovered that a reduction in the speed at which accurate follow up shots can be made is directly proportional to any increase in recoil. The added recoil is the price you pay to get the 40 S&W’s marginally better terminal performance.
Winner: 9mm Luger
9mm vs 40 S&W: Best Loads
Selecting a best load for the 9mm Luger or the 40 S&W is an almost impossible task. This is partly because any factory loads in both cartridges perform very similarly. But it is also partly because what “best” means, varies from shooter to shooter. Some shooters want deep penetration, others want violent bullet upset, and then there are those who like a balance of penetration and bullet upset. When it comes to personal protection, I believe one of the best ways to compare self-defense loads is to look at the crush cavity, which is the size hole makes, determined by its upset diameter and penetration depth. Here are two exceptional performers for both cartridges.
Doubletap loads their 147-grain Controlled Expansion +P 9mm Luger ammo with bonded Winchester bullets, which are some of the best performing self-defense bullets made today. Pushed to +P velocities of more than 1000 fps, these bullets will drive deep and deform with a wide frontal diameter, creating one of the largest crush cavities possible from a 9mm Luger.
Though the packaging has varied over the years, most notably since Federal took over Remington ammunition after Remington went bankrupt, the performance of this 180-grain 40 S&W Golden Saber load has not. Even though it is a subsonic load, it will push to about 14 inches and the bullet will open with a frontal diameter of around three-quarters of an inch. This creates a massive crush cavity of more than six cubic inches.
Outdoorsmen may be more interested in handgun ammunition that is suitable for predator defense. If that’s the case, one of the best options for the 9mm Luger and the 40 S&W are the Federal Solid Core loads. Solid Core ammo is loaded with a hard cast bullet that is coated with a synthetic jacket that limits bore fouling and reduces friction. These bullets are non-deforming and will penetrate more than three feet, which is just what you want if you are about to be mauled by a bear or mountain lion, or maybe even run over by a raging feral hog. These loads can be effective for big-game hunting too.
And the Winner is—Make Mine a Nine
Countless studies have shown that the effective difference between the 9mm Luger and the 40 S&W is not as large as initial testing data suggested. It’s also an established fact that the 9mm can be relied upon to save your life. Let’s not forget how Alaskan hunting guide Phil Shoemaker stopped a charging grizzly with his 9mm pistol. It’s not often that a government agency gets it right, but in this case, I think the FBI did. With the nominal difference in terminal performance, hedging your bets on a pistol that’s easier to shoot, faster, and more accurate seems like a solid, pragmatic decision.
There are more 9mm pistols to choose from, three times the number of factory 9mm loads offered, and more inexpensive 9mm ammunition options available. The 40 S&W is now lost as the middle child between the 9mm and the 45 Auto. A quality pistol chambered for either cartridge can serve you well, but in the end, you can make mine a nine.
