9mm vs. 40 S&W: What’s the Difference Between The Two?

Buzz Hickey, a retired police officer from a very dear TV show of mine, once said, “Caliber don’t matter – bullets just kinda’ kill ya’.” And while there is some truth to this, there are noticeable differences when pitting 9mm vs. 40 S&W against one another.

While the .40 S&W caliber may have been the superior choice back in the nineties, the 9mm round takes first place today. It’s a smaller, lighter cartridge with weaker recoil and more rounds in the magazine. Tests have shown that they’re also more accurate and easier to fire in quick succession.

That’s a summary in case you don’t want to read the article below. I give you a little bit of a history lesson, explain the practical differences between the two, and explain exactly why everyone was crazy about the .40 rounds for a while.

9mm – The Basics

The 9mm caliber, also known as the 9x19mm or the Parabellum, is the most common handgun caliber in the world.

It was designed in 1901 by Georg Luger, and after its bloody demonstration by the German military during the First World War, it was adopted by many militaries around the world.

As the name suggests, the bullet is 9.01 millimeters wide in diameter (0.355 inches) and weighs about 7.45 grams (0.016 pounds).

In theory, the round should only be lethal up to 160 feet, but practice has shown that it’s lethal at greater ranges.

.40 S&W – The Basics

On the other side of the coin, we have the .40 cal Smith & Wesson cartridge.

This cartridge was developed as a direct response to the tragic 1986 FBI Miami shootout, in which two FBI agents lost their lives due to the ineffectiveness of their 10mm handguns.

Smith & Wesson developed a round that weighed more and had a greater diameter, but most importantly – it generated more energy than the standard 9mm round.

This development was an instant hit with law enforcement, with the FBI immediately adopting the 40 S&W as the designated cartridge for its pistols.

When the .40 S&W round was first introduced, 9mm rounds were at the center of criticism for their seemingly low energy output.

This was additionally exacerbated by the FBI Miami shootout, during which Special Agent Jerry Dove engaged a combatant and hit the target with his Smith & Wesson 459, using 9mm rounds, only for the round to stop an inch away from the target’s heart.

The idea behind the .40 S&W round was to retain accuracy, have lower recoil, and have greater stopping power than the 9mm.

And truth be told, the new cartridge initially won the 9mm vs. .40 S&W debate. However, it didn’t hold up that well down the line. The FBI recently released a report stating that the 9mm now delivers better performance than the 40 S&W round because of new technological improvements!

The 9mm Has More Manageable Recoil

While the gap between the two rounds isn’t as large as it was back in the day, 9mm cartridges are known for their controlled recoil.

The .40 S&W has improved its recoil significantly compared to its parent case, the 10mm auto, but the 9mm cartridge is still superior.

This makes the 9mm cartridge highly effective in close-quarters combat and gives it a slight edge over the .40 S&W cartridge.

Weaker recoil allows you to quickly aim at the target as the barrel isn’t thrown too far away from your initial line of sight. Handguns with stronger recoil essentially fire themselves off-target.

However, it must be noted that the difference in recoil is minor and was perhaps more noticeable back in the nineties when 9mm rounds couldn’t be fired with the same power they’re fired with today.

.40 S&W Rounds Deal More Damage to Target

Since they’re larger and release about 50 pounds-feet more than 9mm cartridges, .40 S&W rounds deal more damage to the target. However, the difference in damage dealt is the only area .40 S&W excels at when comparing the two cartridges.

According to the FBI’s report mentioned earlier, these rounds do release more energy and deal slightly more damage. Still, both 9mm rounds and .40 S&W rounds penetrate the target enough (at least 12 inches) to be considered effective.

This means that despite the .40 S&W rounds being more powerful in theory, that power is insignificant and offers you no real advantage compared to the 9mm round.

If anything – 9mm rounds are ‘quieter’, so pair that with a 9mm suppressor, and you have much more of a stealthier effect.

The development of modern ballistic technologies has allowed the evolution of the 9mm round, making it almost as effective as the .40 round.

Do not be fooled – this did allow for the evolution of the .40 round, but when comparing 9mm vs 40 S&W, the 9mm round made more of a leap.

This is mostly due to the propellants used in the bullet itself – the design of the bullet itself remains unchanged.

Because of this, the FBI’s famous testing notes that there’s “little to no noticeable difference in the wound tracks between premium line law Auto enforcement projectiles, from 9mm Luger through the .45 Auto”.

9mm Round Guns Have Greater Magazine Capacities

When the .40 S&W rounds were first introduced, an Act known as the Federal Assault Weapons Ban was introduced (and has since expired). The Act prohibited the sale of handguns with magazines that could hold more than 10 rounds.

At that time, it made more sense to choose a .40 cal over a 9mm – if you’re restricted to 10 rounds regardless of caliber, why not choose the more powerful caliber, right?

In the meantime, however, the ban has expired and it is now legal to own a handgun with a capacity that exceeds 10 rounds.

Since 9mm rounds are smaller in every possible way than .40 S&W rounds, you can fit more in a magazine.

Hundreds of handgun models can fire both 9mm and .40 S&W rounds, and the 9mm models have greater magazine capacity in every single one.

For reference, we can compare the Glock 22 (.40 cal) and the Glock 17 (9mm). As we know, Glock 22 is almost identical to Glock 17, with the only major difference being the difference in caliber.

The Glock 17 has a 17-round magazine capacity, while Glock 22 has a 15-round capacity.

The difference is even greater with the Sig Sauer P226, as the 9mm model has a 20-round magazine capacity. In contrast, the .40 S&W model has a 15-round magazine capacity.

9mm handguns can not be compared to revolvers when it comes to reloading speed (with or without a 9mm speed loader). Revolvers needed to be replaced at the time because of this specific fault.

Considering how long reloading takes, those few rounds can make the difference between life and death in combat or self-defense scenarios. In this regard, the 9mm round is a clear winner of the 9mm vs 40 S&W fight.

9mm Rounds Are Cheaper Than .40 S&W Rounds

Perhaps the most important aspect of the 9mm vs 40 caliber debate, especially if you spend a lot of time at the gun range, is the price.

On average, 9mm ammo is about five cents cheaper than .40 S&W rounds. If you opt for the .40 cal, you’re spending $50 more for every 1000 shots you take!

When it comes to the military and law enforcement choosing their sidearms, it’s easy to understand why this is so important to them. They’re saving millions of dollars annually by choosing 9mm whenever they can.

Let’s be real for a second – the 9mm vs 40 S&W debate isn’t as dramatic as I maybe made it out to be in this article. 9mm rounds are undoubtedly superior, but that doesn’t make .40 S&W rounds a bad choice in any way.

Both of these calibers have proven their effectiveness in the field. However, 9mm rounds are cheaper, cause less recoil, and, most importantly – allow you to fit more in your magazines.

Considering that, I’d recommend you choose a 9mm handgun over a .40 cal handgun, if you have the option.

Let us know in the comments what your experience has been.