9mm vs 40 – 2022 In-Depth Breakdown

From the Luger of the Kaiser’s soldier in WW1 to the everyday carry handguns of today’s civilians, the 9 mm Parabellum is now more than 120 years old, and is nowhere close to losing its first rank in popularity. Then comes the venerable .40 S&W, which was designed to be the official round of the FBI, but ended up being a popular self defense and bear defense round. 

This comparison will weigh the features, pros and cons of both these cartridges. Which may seem worlds apart superficially, but have a lot in common that you would really expect. 

9mm vs 40

Here’s a quick table to outline the pros and cons of these two rounds.

9mm Overview

9×19 mm Parabellum, also known as the 9mm Luger, or 9mm, is a rimless, tapered firearms cartridge, popular for use in handguns and submachine guns. It was designed in 1901 by the famous Austrian firearms designer Georg Luger. It was the second refinement of the 7.62×25 mm Borchardt cartridge designed for the Borchardt C93 pistol, which is also credited to be the first popular semi-auto pistol. 

Starting 1904, the German military forces started adopting this round, and by 1908 a large chunk of the German military were fielding it as their handgun round. The 9mm is also the official standard handgun cartridge of the NATO forces, and is also the most popular handgun cartridge in the world. 

The round was designed to be lethal out to a range of 50 meters (~55 yards), and is very accurate out to that distance. There is a wide range of load and bullet options for this cartridge, and the price is extremely lucrative. 

The compact design of the cartridge allows more rounds to be had in a magazine, especially the double stack magazines. The bullet diameter is appropriate to cause enough damage, and the recoil is exceptionally controllable. This balance of power and controllability is what made this cartridge insanely popular among the military, LEO’s and civilian population. 

40 Overview

The .40 Smith & Wesson, also known as the .40 Cal or .40, is a modification of the 10 mm Auto cartridge. It is a rimless, straight walled handgun cartridge that fires a .40 caliber bullet. It all started after the 1986 FBI Miami shootout, when the FBI lost the lives of two agents in the incident and began rethinking to replace their existing underpowered cartridges. 

The concept sprung out from the 10 mm Auto which was selected by the FBI after this incident to replace their existing rounds. The 9 mm and .45 ACP were also in the competition, but were discarded. The 10 mm Auto was found to be overpowered and less controllable, so the FBI asked Smith & Wesson which was working on this to lessen the amount of powder.

S&W saw this as an opportunity to shorten the overall length of the 10 mm Auto, and thus the .40 S&W round was born. A cartridge that can fire a 0.40 caliber bullet, with handguns similar to the size of the 9mm pistols. The development of the .40 S&W solved two problems at once.

It’s popularity rose after the Federal Assault Weapons Ban of 1994 which prohibited mags with more than ten rounds. Although the ban has now expired, the .40 S&W is still a significantly popular round among law enforcement agencies in the United States and several other countries of the world. 

9mm vs 40: Cartridge Specs

	9mm	.40 S&W
Bullet Diameter	0.355 in (9.10 mm)	.400 in (10.2 mm)
Neck Diameter	0.380 in (9.65 mm)	.423 in (10.7 mm)
Base Diameter	0.391 in (9.93 mm)	.424 in (10.8 mm)
Case Length	0.754 in (19.15 mm)	.850 in (21.6 mm)
Overall Length	1.169 in (29.69 mm)	1.135 in (28.8 mm)
Case Capacity	13.30 grains	19.3 grains
Max Pressure (SAAMI)	35,000 psi	35,000 psi
Typical Casing Material	Brass	Brass
Typical Bullet Weight (gr)	115-147 grains	135-180 grains

The 9mm is clearly a smaller and thinner case compared to the .40 S&W. It fires a 0.355 inch diameter bullet, which is a millimeter shy from the .40 S&W. The only noticeable similarity in the dimension characteristics of these rounds is the maximum pressure rating, which is the same. 

The .40 S&W has characteristics similar to the 10 mm Auto, like headspacing, bullet diameter and some bullet weights. As far as the 9 mm is concerned, it features a smaller overall length (only by a millimeter), and a 50% less case capacity. Despite having lesser power, the 9 mm has the same chamber pressure as the .40 S&W. 

The 9 mm bullets have weights in the range of 115 to 147 grains, whereas the .40 S&W fields bullet weights between 135 and 180 grains. This corroborates that extra case capacity to hold more powder for the .40 S&W rounds. 

The .40 S&W has been designed to deliver less recoil than its 10 mm and .45 ACP counterparts. The 9 mm on the other hand, features a more controllable and compact design. This also ensures that more rounds of the 9 mm can be held inside a similar sized magazine, compared to the .40 S&W. 

9mm vs 40: Ballistics

9mm vs 40: Trajectory

Here is the reference data for analyzing the trajectory of these rounds, and to infer their accuracy characteristics. 

9mm

4.49” barrel/BC 0.120/115-grain FMJ	4.49” barrel/BC 0.150/124-grain JHP	4.49” barrel/BC 0.200/147-grain FMJ
25 yds: 0 “ Drop	25 yds: 0 “ Drop	25 yds: 0 “ Drop
50 yds: 0.9 “ Drop	50 yds: 0.9 “ Drop	50 yds: 1.4 “ Drop
75 yds: 3.7 “ Drop	75 yds: 3.8 “ Drop	75 yds: 5.2 “ Drop
100 yds: 8.7 “ Drop	100 yds: 8.8 “ Drop	100 yds: 11.5  “ Drop
125 yds: 16.1 “ Drop	125 yds: 16.1 “ Drop	125 yds: 20.3 “ Drop

.40 S&W

5” barrel/BC 0.110/135-grain Hydra-Shok	5” barrel/BC 0.130/155-grain FMJ	5” barrel/BC 0.170/180-grain FMJ
25 yds: 0 “ Drop	25 yds: 0 “ Drop	25 yds: 0 “ Drop
50 yds: 0.8 “ Drop	50 yds: 0.9 “ Drop	50 yds: 1.4 “ Drop
75 yds: 3.7 “ Drop	75 yds: 3.8 “ Drop	75 yds: 5.3 “ Drop
100 yds: 8.6 “ Drop	100 yds: 8.9 “ Drop	100 yds: 11.6 “ Drop
125 yds: 15.9 “ Drop	125 yds: 16.3 “ Drop	125 yds: 20.7 “ Drop

The trajectory data for both these rounds seems quite interesting, because the difference in bullet weight, and case capacity is quite large. The 9mm and .40 S&W have almost the same trajectory out to 100 yards, with absolutely no difference out to fifty. 

The flight path for the lightweight bullets of these rounds is practically the same, with the .40 S&W gaining a slight edge beyond 100 yards. These are handgun rounds, and will seldom be used for that kind of distance. However, the data clarifies that there will be no difference in the trajectory. 

Considering the heavy loads for these cartridges, the advantage starts coming towards the 9 mm after a range of 100 yards, but only by a small margin. The reason is of course the lighter bullet weight for this. 

Talking about the wind resistance, the 9 mm bullets almost always have a better ballistic coefficient when compared to the .40 S&W. This means that on a windy day, the 9 mm will have a better chance of accurate performance, but again, only by a small margin.

9mm vs 40: Velocity & Kinetic Energy

Now take a look at the data table comparing the velocity and energy characteristics of these rounds at different distances and with different bullet types. The best/ideal barrel length as recommended by the manufacturers was used for testing these rounds to get ideal results. 

9mm

4.49” barrel/BC 0.120/115 grain FMJ	4.49” barrel/BC 0.150/124 grain JHP	4.49” barrel/BC 0.200/147 grain FMJ
C25 yds: 1,106 ft/s, 312 ft.lbs	25 yds: 1,095 ft/s, 330 ft.lbs	25 yds: 976 ft/s, 311 ft.lbs
50 yds: 1,048 ft/s, 280 ft.lbs	50 yds: 1,049 ft/s, 303 ft.lbs	50 yds: 953 ft/s, 293 ft.lbs
75 yds: 1,001 ft/s, 256 ft.lbs	75 yds: 1,010 ft/s, 281 ft.lbs	75 yds: 933 ft/s, 284 ft.lbs
100 yds: 961 ft/s, 236 ft.lbs	100 yds: 977 ft/s, 263 ft.lbs	100 yds: 914 ft/s, 273 ft.lbs
125 yds: 927 ft/s, 219 ft.lbs	125 yds: 948 ft/s, 247 ft.lbs	125 yds: 896 ft/s, 262 ft.lbs

.40 S&W

5” barrel/BC 0.110/135-grain Hydra-Shok	5” barrel/BC 0.130/155-grain FMJ	5” barrel/BC 0.170/180-grain FMJ
25 yds: 1,116 ft/s, 373 ft.lbs	25 yds: 1,095 ft/s, 413 ft.lbs	25 yds: 972 ft/s, 377 ft.lbs
50 yds: 1,051 ft/s, 331 ft.lbs	50 yds: 1,043 ft/s, 374 ft.lbs	50 yds: 946 ft/s, 358 ft.lbs
75 yds: 999 ft/s, 299 ft.lbs	75 yds: 1,000 ft/s, 344 ft.lbs	75 yds: 923 ft/s, 340 ft.lbs
100 yds: 957 ft/s, 274 ft.lbs	100 yds: 963 ft/s, 319 ft.lbs	100 yds: 901 ft/s, 324 ft.lbs
125 yds: 920 ft/s, 254 ft.lbs	125 yds: 931 ft/s, 298 ft.lbs	125 yds: 881 ft/s, 310 ft.lbs

Both these rounds are supersonic within a range of 25 yards, which is a good factor in terms of accuracy. The light to medium weight loads for both these rounds stay supersonic out to 50 yards, whereas the heavier bullet weights begin to lose that status right after 25 yards. 

The heavy loads for both these rounds are innately subsonic, at and beyond 25 yards. These are the better choices for use with suppressors. Such ammo also projects a milder recoil, which is a matter of concern with .40 S&W ammo. Additionally, subsonic ammo is also easy on the barrel and other internals of the firearm, and promotes slower wear and tear. 

The 9 mm is also available in a variety of loads, including the popular +p loads that can deliver higher velocity. 

Moving on to the energy characteristics, the .40 S&W is always a clear winner regardless of range or even bullet weight. The difference in the energy characteristics for these rounds is not too much, especially beyond 50 yards. However, a 50 fpe difference can cause a significant impact on a hostile, when you are engaged in a self-defense situation. 

9mm vs 40: Stopping Power

The stopping power of a round describes its ability to decimate a target as quickly as possible. This factor is important in understanding how well a round will perform against different targets, and if it is suitable for home defense, hunting, breaking armor, tactical applications, or anything else. 

9mm vs 40: Momentum & Sectional Density

The two definitive characteristics for measuring the stopping power of a round are momentum, and sectional density. Here are the SD and momentum values for the rounds compared in the above tables. 

9mm

4.49” barrel/BC 0.120/115 grain FMJ Sectional Density: 0.130	4.49” barrel/BC 0.150/124 grain JHP Sectional Density: 0.141	4.49” barrel/BC 0.200/147 grain FMJ Sectional Density: 0.167
25 yds: 18 ft.lb-s	25 yds: 19 ft.lb-s	25 yds: 18 ft.lb-s
50 yds: 17 ft.lb-s	50 yds: 18 ft.lb-s	50 yds: 17 ft.lb-s
75 yds: 16 ft.lb-s	75 yds: 17 ft.lb-s	75 yds: 16 ft.lb-s
100 yds: 15 ft.lb-s	100 yds: 17 ft.lb-s	100 yds: 19 ft.lb-s
125 yds: 15 ft.lb-s	125 yds: 16 ft.lb-s	125 yds: 18 ft.lb-s

.40 S&W

5” barrel/BC 0.110/135-grain Hydra-Shok Sectional Density: 0.120	5” barrel/BC 0.130/155-grain FMJ Sectional Density: 0.137	5” barrel/BC 0.170/180-grain FMJ Sectional Density: 0.159
25 yds: 21 ft.lb-s	25 yds: 24 ft.lb-s	25 yds: 24 ft.lb-s
50 yds: 20 ft.lb-s	50 yds: 23 ft.lb-s	50 yds: 24 ft.lb-s
75 yds: 19 ft.lb-s	75 yds: 22 ft.lb-s	75 yds: 23 ft.lb-s
100 yds: 18 ft.lb-s	100 yds: 21 ft.lb-s	100 yds: 23 ft.lb-s
125 yds: 17 ft.lb-s	125 yds: 20 ft.lb-s	125 yds: 22 ft.lb-s

The sectional density (SD) of a bullet is the ratio between its mass and cross-sectional area. The higher this value, the more penetration can be expected by a bullet. An SD of less than 0.200 is considered good for small game animals, an SD between 0.220 and 0.270 is good for deer-sized game, that between 0.270 to 0.300 is good for bigger game like elk, and anything above that is suitable for thick-skinned dangerous game. 

As far as handgun rounds are considered, the most common calibers generally feature an SD of less than 0.200. As you can see in the data, the 9 mm bullets show a better SD value against .40 S&W in comparable bullet weights. This data is also true in real life, and 9 mm bullets deliver better penetration than .40 S&W. 

Law enforcement agencies use 12 inches of ballistic gel as the penetration standard. In tests, 9 mm (124-grain JHP) delivers an average penetration of 18.4 inches, whereas the .40 S&W (180 grain JHP) delivers an average penetration of 15.1 inches. However, the latter creates a marginally larger wound cavity due to the larger bullet diameter. 

The value of momentum for a round describes the efficiency of energy transfer, which helps in creating a bigger wound channel. The .40 S&W has a higher value of momentum at every range, and hits harder than the 9 mm. 

9mm vs 40: Use Cases & Effective Range

Both these rounds are quite comparable, and yet so different in some matters. Each of these has their own specific utility in different situations. 

Home and Self Defense

The first and possibly the most common use of handguns is self defense. A majority of people use them for EDC (everyday carry) and CCW (Concealed Carry) because of their small size, easy handling and inconspicuous carry. 

If we compare these two rounds, the 9 mm is undoubtedly the most popular self defense handgun cartridge today, and also of all time. The reason is clear and simple, 9 mm rounds have low recoil and allow the use of double stack magazines that hold more rounds. 

In my opinion, and also as the common consensus of majority of firearm owners and authoritative figures on the topic of self defense. A 9 mm round is the perfect choice for self and home defense because of its controllability, and the wide range of handgun and ammo options available on the market. 

On the other hand, the .40 S&W is a hard-hitting round with slightly more stopping power, and it can get the job done in fewer shots. However, one has to be very trained and proficient in the matters of self-defense to really control the anxious nerves during such an encounter. Plus, the .40 S&W also has a higher recoil and a smaller mag size. 

On a side note, some states have high capacity magazine bans that limit the mag size to 10 rounds. A .40 S&W can be a better choice in such situations. 

Active Duty and Tactical 

The .40 S&W was designed by downsizing the 10 mm Auto, which was already in use by the FBI. The .40 cal has widely been used by many police departments across the country, and also the world. The good stopping power makes it a great option for active duty applications. 

However, the controllability issues caused by this round, and the large size of weapons is what prevented it from being a universally useful firearm among the forces. So the FBI switched back to the 9 mm, as did most police departments. 

The 9 mm has better penetration, more controllability, and higher mag capacity. Plus, the handguns for 9 mm also come with a wide range of customizability options. 

Hunting

The .40 S&W has quite some potential as a hunting round, especially when talking about small to some medium-sized game like hogs. It is also widely used as a bear defense gun, mostly as an alternative to the 10 mm Auto. 

The 9 mm on the other hand can be used for hunting small game, but it does not have sufficient energy to kill medium sized game. 

9mm vs 40: Costs, Availability, & Compatibility

Now let’s look at the availability and economics for these rounds, and if there is a good scope for customizability. 

Apt Pricing and Easy to Find

The 9 mm is among the most perfectly priced and readily available cartridges on the market. There is no ammo seller that does not carry the 9 mm, and as far as the price is concerned, it ranges from as low as $0.50 to as high as $1.80. On the other hand, the .40 S&W is slightly more costly than this with a range of $0.60 to $2.5 per round. 

Although, as far as general ammo choices are concerned, both these rounds are closely comparable. 

Talking about availability, popular rounds like the 9 mm can quickly fly off the market shelves in situations like the Covid-19 pandemic buying. This did happen, but luckily the 9 mm is quite common and could be availed at exorbitant prices when found. The .40 S&W is also readily available and is a better choice for ‘panic-buying’ situations since it will not just disappear from market shelves. 

Wide Range of Options

The 9 mm round has been around for more than a century now. There is an exceptionally wide range of handguns and also submachine guns available for this cartridge. It is like the AR-15 of the handgun world, with a lot of options that can be highly customized. 

The .40 S&W is also quite popular and comes in a wide range of handgun models to choose from. The Glock 22 and S&W M&P40 are quite popular. So no matter which of these cartridges you choose, you will never run out of options for firearms and customizability. 

Bottom Line

The 9 mm is a century-old cartridge that is still the most popular handgun chambering of the world. It is extremely popular for self-defense, law enforcement, and military applications. The ammo is cheap and easily available, plus there is a wide range of customizable guns to choose from.

The .40 S&W was modeled by downsizing the 10 mm Auto round and has similar stopping power and performance characteristics. It is also readily available and quite cost-effective for its size. 

Comparing these two, the 9 mm is a more compact and controllable round with better penetration. Whereas the .40 S&W offers more power and energy but at the cost of recoil.