Headstamp-to-Headstamp: 9mm vs. .40 S&W

Michael Crites


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9mm vs 40SW - Ballistics & Power - Cover

Headstamp-to-Headstamp is our series aimed at helping you grok everything ammo.

The debate over the most effective handgun caliber is as old as time itself. In this article, we will compare two of the most popular calibers available today – the 9mm to the .40 S&W.

In This Article:

9mm vs. .40 S&W Comparison

At its most basic, it’s reasonable to conclude that the .40 caliber S&W has more stopping power, kinetic energy, and superior ballistics to the target, which will lead to larger and potentially more lethal wounds (although 9mm ammunition is powerful in its own right).

Because of this, many people prefer the .40 S&W for home defense. That said, when it comes to defining effectiveness, stopping power is just one of the many considerations we’ll explore.

From left to right: 9mm, .40 S&W, & .45ACP pistol cartridges
The 9x19mm Luger, .40 Smith & Wesson, and .45 AUTO
9mm vs 40 SW - Glocks
There’s no discernable difference between the ejection ports of these Glocks despite the difference in chambering. All of the difference is in the business end of these cartridges.

The 9mm

9mm ammo headstamps
9mm ammo headstamps

The 9mm parabellum is a bullet that the German manufacturer Deutsche Waffen- und Munitionsfabriken first developed in 1902 for the semi-automatic 9mm pistol, the Luger.

Around 60% of police departments use 9mm ammo and it continues to be the most popular cartridge type in the world.

9mm Ballistics Gel Tests

9mm 124 gr gel ballistics test
Shooting the 9mm +P 124 gr JHP by Federal gives reasonable penetration depth and expansion. Source: LuckyGunner

The 9mm has maintained its popularity for several reasons. For one, the design of the 9mm round enables it to lose less than 10% of its velocity at 100 yards, so the round delivers well within its optimal operating window. This keeps its penetration within acceptable depths but provides stopping power well beyond reasonable handgun range. 

Modern 9mm design innovations give it similar ballistics to the .40 S&W and the .45 ACP but with the benefit of increased magazine capacity over those two cartridges. 

The weight of a 9mm round can vary significantly – from 115 to 147 grains – giving users a wide variety of options, and delivering ballistic energy anywhere from 355 to 455 ft-lbs. The case length of different 9mm cartridges can vary from 17 to 25 mm. The standard 9x19mm Parabellum has a standardized case length of 19.15mm, or about ¾ an inch, which is just about a tenth of an inch shorter than the .40 S&W, which comes in at .850 inch, or 12.6mm. 

The 9mm is also a popular choice for the military and police departments because it’s – frankly – cheap. A 9mm bullet normally costs as little as 14 cents per round. Although bullet prices may vary (cough, cough, COVID shortage) these per-round savings can quickly add up when shooting thousands of rounds at the range or ordering industrial quantities.

The 9mm cartridge also delivers less felt recoil than similar calibers, While a .22 LR has a felt recoil measured in ounces, a 124 grain 9mm round generates around 4.5 lbs of felt recoil while the larger 160 grain .40 S&W generates 50% more felt recoil – coming in at 6.3 lbs on average. This controllable recoil combined with its shorter case and potential for higher magazine capacity in a smaller overall frame also makes the 9mm a popular choice for concealed carry.

The .40 S&W

Bullet Comparison 9x19mm, .40 S&W, 10mm Auto,
Bullet Comparison 9x19mm, .40 S&W, 10mm Auto

The .40 S&W is a 40 caliber cartridge that Smith & Wesson designed with Winchester at the request of the FBI after the 1986 Miami shootout. The FBI wanted a cartridge that had the same power as a 10mm cartridge but with a bullet design that could fit into a medium-frame 9mm handgun. 

Achieving the FBI’s requirements meant using less powder in the 10mm case, which allowed them to both shorten the case enough to fit the medium-framed 9mm handgun and load it with a 180-grain JHP bullet. This produced ballistic performance identical to the FBI’s reduced-velocity 10mm cartridge. And thus, the .40 S&W was born.

.40 S&W Ballistics Gel Tests

40 S&W 180 gr gel ballistics test
The heavier bullet of the 180 gr HST by Federal Premium gives more penetration and expansion than the 9mm alternative. Bigger bullets = more expansion opportunities.

The standard weight for a .40 S&W is 180 grains, but he 40 cal round’s weight can vary from 115 to a very chunky 200 grains depending on the bullet type. This additional weight has a direct impact on the ballistic energy the round can transfer to its target and generally ranges anywhere from 460 to 588 ft-lbs.

This gives it more stopping power than smaller ammunition types – making for a more effective self defense load – but the heavier lead means more felt recoil, all things being equal.

Different features of the 9mm vs .40 S&W

In the sections below, we will break down the different aspects of each cartridge and give a nod to the best round for each category.

9mm vs 40 SW - Case Comparisons 2
Here you can see the relative difference in the case heights and diameters between the .40 S&W (left) and 9mm (right). These small differences have a significant practical impact.


As mentioned above, the average cost of a 9mm bullet is around 14 cents per round, which is a major part of its appeal. The 9mm is also ubiquitous – there are very few gun shops wherein you wouldn’t find a box of 9mm on the shelf.

The average cost of a .40 S&W is around 19 cents per round – almost 30% more than the 9mm. While this is a fair price for ammunition it’s still considerably more expensive than 9mm bullets.

If you are someone who frequents the range, sticking with a 9mm will keep your ammunition costs down. Although the prices of these two rounds don’t differ drastically, it adds up at the end of the day. For its relatively cheap price per round, the 9mm wins in terms of cost.


The 9mm round can deliver anywhere from 355 to 455 ft-lbs of energy depending on the weight of the bullet, which translates into a ballistic gel penetration cavity of 41 to 84 ml. This is certainly enough to be plenty lethal with sufficiently accurate shot placement, it isn’t as powerful as larger-caliber rounds.

The .40 S&W cartridge, on the other hand, can deliver significantly more energy to a target – from 460 to 588 ft-lbs on average. 

This clearly outperforms most 9mm rounds and translates into a wound cavity around 6% larger than the 9mm. On the surface, this theoretically means that the .40 S&W has more stopping power than the 9mm.

This stopping power conclusion is further supported by a 1992 Ohio police study which found that the 9mm bullet required 2.45 rounds fired to incapacitate an assailant. The .40 S&W, on the other hand, required only 2.36 rounds on average to achieve incapacitation.

The .40 S&W transfers more energy to the target with nearly identical accuracy, drift, and drop as the 9mm – and on average requires fewer shots to stop a bad guy. We’d give it the edge when it comes to ballistics.


ACCURACY RESULTS: (Tested Unit: Stoeger Model 8000 Cougar)





AVG> GROUP (in.)

.40 S&W;

CCI Blazer HP





Federal Hydra Shok JHP





Remington Golden Saber





Speer Gold Dot





Winchester JHP






CCI/Blazer TMJ





Federal JHP





Hornady XTP HP





PMC Starfire





Remington Golden Sabre





Winchester SXT





Magazine Capacity

The 9mm is the smaller of the two cartridges, which means it has the potential for higher magazine capacity. This adds to its appeal with law enforcement, military, and special forces applications because you have more rounds at your disposal before a reload. In a firefight, you may not get the chance to reload if the action is moving at a quick pace. A few additional rounds can make all the difference.

For home defense and concealed carry purposes, this might not make much of a difference, and in fact, can work against you when it comes to concealability. Statistics from the FBI state that the average gunfight consists of 3 shots over a 3 second period. The average amount of shots fired in home defense is just 2 rounds. So, do you need a high-capacity magazine if your focus is home or self-defense?

Still, the 9mm does have a larger magazine capacity, so it does technically win this round.

Recommended Pistols

The M&P Shield M2.0 is a second-generation version of Smith & Wesson’s now-classic polymer-framed striker-fired M&P line of pistols is establishing a new standard for carry and handgun enthusiasts everywhere. They’re incredibly reliable, built with S&W quality, and as popular in some circles as the polymer behemoth, the Glock. The Shield is also available in an EZ variant, has an easier-to-rack slide – making the Shield a top option for new shooters.

An already impressive pistol in the Gen 4 Glock 17, the Gen5 MOS, ups the ante even further with the addition of a Modular Optic System (MOS). The slide is machined to ease mounting of optics, so with the swap of an adapter plate, you can mount your favorite mini red dot sights to the rear of the slide.

The M&P 40 Shield M2.0 is the same great S&W Shield platform as the 9MM version, with a slightly reduced capacity – taking the 9MM’s 7 or 8 +1 down to 6 or 7+1. On the upside the .40 S&W version drops almost a full ounce, so you get a little more bang in a lighter package.

The Italian manufacturer’s PX4 Storm is a fascinating pistol, beloved by many since its release in 2004. The PX4 uses a rotating barrel system, which is designed to reduce wear on the chrome-lined barrel and felt recoil. It’s one of the few pistols that doesn’t use the Browning action, and it’s just as at home in a home defense role as EDC or even a competition pistol thanks to the light recoil impulse of the rotating barrel.

Closing thoughts

While not separated by a world of difference, the 9mm and .40 S&W round have their respective strengths and weaknesses which make them advantageous for different scenarios. The 9MM offers lighter recoil, a higher capacity magazine, a lower cost per round, with reasonable lethality. A .40 S&W gives you more power upfront & more lethality but at the cost of capacity. 

These are both great choices that have a huge gun pool to choose from, with 9mm still the king of the hill and the .40 S&W only trailing the .45 ACP in terms of gun options at most retailers.

3.6/5 - (87 votes)

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