9mm vs 45 – Valid 2022 Argument?

The 9mm Luger was Germany’s favorite sidearm cartridge during WWII, and the Americans trusted the .45 ACP. After more than a century of their introduction, these cartridges remain relevant, with 9 mm being the most popular handgun cartridge around the world.

While most differences between these two rounds are superficial, each of these is a reliable selection and has its own fanbase. However, has the immense popularity of the 9mm made the .45 ACP to fade out? Let’s answer this question in detail.

9mm vs 45

Check out this quick side-by-side comparison with the pros and cons of the 9 mm and .45 ACP cartridges. 

9mm Overview

The 9×19 mm Parabellum, aka the 9 mm Luger or 9 mm Parabellum is a rimless and tapered firearms cartridge that fires a 0.355 in/9.01 mm diameter bullet. It was invented by the legendary Austrian firearms designer George Johann Luger in 1901, who is credited with creating the famous Luger pistol. 

The round was a modification of the 7.62×21 mm handgun round which was previously derived from the 7.62×25 mm Borchardt round. These parent cartridges were also developed by Gerog Luger. The shortened length of the 9mm Luger cartridge helped with developing more compact handguns and angled grips.

It was the official sidearm cartridge of the German military forces in both World Wars and has been used in many pistols, revolvers, and submachine guns since then. Today, the 9mm Luger is the most popular pistol cartridge across the world for both civilian and military populations. It is also the standard sidearm cartridge of NATO forces and is designated as 9 mm NATO. 

The short design and low recoil help with carrying more rounds in a smaller firearm and also improve the control of the weapon during successive shots. High pressure loadings designated as +P and +P+ are also prevalent to some extent for increasing the velocity and penetrating power of the bullet. 

45 Overview

The .45 ACP (Automatic Colt Pistol), aka the .45 Auto or 11.43×23 mm, is a rimless, straight-walled cartridge with a 0.455-inch diameter bullet. This cartridge was designed by John Moses Browning in 1904 and was adopted by the U.S Military in 1911 as the standard sidearm cartridge for M1911 pistols. 

Browning had already been working on a .41 caliber cartridge in 1904, and later improved it to develop the .45 ACP as the military desired the power of the .45 Colt already in use with SA revolvers. The need for a more powerful round was felt after the .38 Long Colt proved inefficient during the Philippine-American war.

The .45 ACP cartridge was significantly shorter than the .45 Colt and was offered in a semi-auto pistol. It became the longest-serving sidearm cartridge for the United States Military until being largely replaced by the 9 mm Parabellum in the 1980s. 

It is a cartridge fairly popular among civilian and military users, although it requires a significant amount of training to tame its recoil. The fact that these rounds are supersonic makes them ideal for use with suppressors. While the defense forces had to phase them out to address controllability, mag capacity, and weight issues, this is a fairly popular and absolutely loved cartridge for purists. 

9mm vs 45: Cartridge Specs

Check out the side-by-side comparison of the dimension of 9 mm Parabellum and .45 ACP cartridges. 

	9 mm	.45 ACP
Bullet Diameter	0.355 in (9.10 mm)	.450 in (11.4 mm)
Neck Diameter	0.380 in (9.65 mm)	.473 in (12.0 mm)
Base Diameter	0.391 in (9.93 mm)	.476 in (12.1 mm)
Case Length	0.754 in (19.15 mm)	.898 in (22.8 mm)
Overall Length	1.169 in (19.69 mm)	1.275 in (32.4 mm)
Case Capacity	13.30 grains	26.7 grains
Max Pressure (SAAMI)	35,000 psi	21,000 psi
Typical Casing Material	Brass	Brass
Typical Bullet Weight (gr)	115-147 grains	165-230 grains

The 9 mm Parabellum uses a 0.355-inch diameter bullet or the same as the .380 ACP. The case length of 19.15 mm makes it a very appropriate length for use in compact or even subcompact handguns. It is loaded at a high pressure of 35,000 psi as per SAAMI regulations, with hotter loads available for more velocity. 

The most common bullet weights used for 9 mm cartridges range between 115 to 147 grains. The military prefers the 124-grain bullet for combat and many civilians prefer the heavy 147 grain bullets for EDC and self-defense. 

The .45 ACP is a larger and bigger bullet with a diameter of 0.450 inches. It is a slightly longer case than the 9 mm at 22.8 inches and has almost twice the case capacity. However, .45 ACP bullets are loaded at far lower pressures to prevent quick wear and tear on the internal parts by making the bullet fly at only supersonic speeds. 

The most common bullet weights for the .45 ACP range from 165 to 230 grains with the two most popular being the 185 and 230-grain bullets. The big and heavy bullets deliver a larger wound channel and penetration, but lack on the trajectory. We will understand these things in detail in the upcoming sections. 

9 mm vs 45 ACP: Ballistics

Ballistics refers to the motion characteristics of a moving projectile and how it behaves over a specific distance. The major characteristics covered under ballistics are trajectory, velocity, and kinetic energy of the bullet. 

These factors prove fundamental in determining if a specific load will be suitable for long or short range, and against any particular type of target. This in turn determines the most suitable application for a round and what you should expect from it. 

9mm vs 45: Trajectory

I have compiled the trajectory data for the 9mm and .45 ACP cartridges using the most common bullet weights and types. Although a handgun is mostly considered appropriate for use within 50 yards (and that’s what most militaries preach), I have taken the maximum range of 125 yards to check out on the maximum potential of each of these. 

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

45 ACP

5.03” barrel/BC 0.130/165 grain Hydra-Shok	5.03” barrel/BC 0.070/185 grain FMJ Semi Wadcutter	5.03” barrel/BC 0.190/230 grain FMJ
25 yds: 0 “ Drop	25 yds: 0 “ Drop	25 yds: 0 “ Drop
50 yds: 1.2 “ Drop	50 yds: 3.1 “ Drop	50 yds: 2 “ Drop
75 yds: 4.7 “ Drop	75 yds: 10.6 “ Drop	75 yds: 6.9 “ Drop
100 yds: 10.6 “ Drop	100 yds: 23 “ Drop	100 yds: 15 “ Drop
125 yds: 19.1 “ Drop	125 yds: 40.6 “ Drop	125 yds: 26.1 “ Drop

While the 9 mm has been shot using a 4.5 inches barrel (most common length for Glock 17), the .45 ACP has been fired using the most common M1911 Government Model barrel length of 5 inches. Plus, both these handguns were zeroed at a range of 25 yards for better estimation of short and long range trajectories. 

The 9 mm will always prove to be a flatter shooting round out to the maximum range because of the lightweight bullet and close-to-supersonic speeds. Inside the most common effective range of 50 yards, the 9 mm will always have a drop of about one inch on average. This is a significant contributor to why this caliber is widely popular, but we’ll discuss more on that in the further sections.

As far as the .45 ACP is concerned, it shoots quite flat within a range of 40-45 yards but requires a lot of adjustment beyond that. This means if a hostile is running away from you and you target the torso, the bullet will most likely land around the thigh. Although, the power of the .45 ACP will make sure to incapacitate it. 

9mm vs 45: Velocity & Kinetic Energy

The velocity characteristics of a bullet describe how fast it moves at a specific distance, which further helps in estimating its trajectory, impact force, and other factors. The kinetic energy describes how much energy does a bullet retains at any point and it helps determine how much damage a bullet can cause and if it is suitable for small or big targets. 

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: 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

45 ACP

5.03” barrel/BC 0.130/165 grain Hydra-Shok	5.03” barrel/BC 0.070/185 grain FMJ Semi Wadcutter	5.03” barrel/BC 0.190/230 grain FMJ
25 yds: 1,014 ft/s, 377 ft.lbs	25 yds: 735 ft/s, 222 ft.lbs	25 yds: 844 ft/s, 364 ft.lbs
50 yds: 976 ft/s, 349 ft.lbs	50 yds: 703 ft/s, 203 ft.lbs	50 yds: 828 ft/s, 350 ft.lbs
75 yds: 942 ft/s, 325 ft.lbs	75 yds: 672 ft/s, 185 ft.lbs	75 yds: 813 ft/s, 338 ft.lbs
100 yds: 912 ft/s, 305 ft.lbs	100 yds: 642 ft/s, 170 ft.lbs	100 yds: 799 ft/s, 326 ft.lbs
125 yds: 885 ft/s, 287 ft.lbs	125 yds: 615 ft/s, 155 ft.lbs	125 yds: 785 ft/s, 315 ft.lbs

While the lightweight loads of the 9 mm ammo are inherently supersonic, the heavier and more common loads like the 147 grain are subsonic. Supersonic loads shoot flatter and carry slightly more momentum (more on that later) for higher damage. Velocities higher than 1,000 fps for the 9 mm loads clearly explain their respectably flat trajectory out to 75 yards. 

The .45 ACP is a strictly subsonic round and as we have seen already it loaded at almost half the pressure. Those 230 grain bullets when fired from a short barrel of five inches should be supersonic to prevent unnecessary wear and tear on the mechanism. Additionally, such a short barrel length will have no significant impact on velocity, range, or accuracy, so there’s no point. 

9mm vs 45: Stopping Power

The stopping power of a bullet describes how quickly and effectively it can stop a target dead in its tracks. The factors useful for determining the stopping power of a bullet include penetration (which is evaluated using sectional density) and momentum. 

In layman terms, the stopping power will describe how quickly and with the least number of bullets can a round do its job. 

9mm vs 45: Momentum & Sectional Density

The momentum of a moving object is the product of its mass and velocity and describes the effectiveness of energy transfer. On the other hand, the sectional density is the ratio of the object’s mass to its cross sectional area. Keeping the other factors similar (velocity, bullet type, expansion), the higher the sectional density (SD) of a bullet, the better penetration it delivers. 

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: 20 ft.lb-s
50 yds: 17 ft.lb-s	50 yds: 18 ft.lb-s	50 yds: 20 ft.lb-s
75 yds: 16 ft.lb-s	75 yds: 17 ft.lb-s	75 yds: 19 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

45 ACP

5.03” barrel/BC 0.130/165 grain Hydra-ShokSectional Density: 0.116	5.03” barrel/BC 0.070/185 grain FMJ Semi Wadcutter Sectional Density: 0.131	5.03” barrel/BC 0.190/230 grain FMJ Sectional Density: 0.162
25 yds: 23 ft.lb-s	25 yds: 19 ft.lb-s	25 yds: 27 ft.lb-s
50 yds: 23 ft.lb-s	50 yds: 18 ft.lb-s	50 yds: 27 ft.lb-s
75 yds: 22 ft.lb-s	75 yds: 17 ft.lb-s	75 yds: 26 ft.lb-s
100 yds: 21 ft.lb-s	100 yds: 16 ft.lb-s	100 yds: 26 ft.lb-s
125 yds: 20 ft.lb-s	125 yds: 16 ft.lb-s	125 yds: 25 ft.lb-s

Despite the heavier bullet weights for the .45 ACP, it can be clearly inferred from the data that 9 mm bullets will always offer better SD in comparable weights. Since the 9 mm bullet is 0.355 inches in diameter compared to the 0.450 inches of .45 ACP, it can pinpoint all the force on a smaller area of the target. This in turn increases penetration on an object, and hence the damage. 

However, the .45 ACP may not offer too deep penetration, but it moves at about a 30-40% greater momentum. What it means is that a .45 ACP may not go deeper but it will create a larger wound cavity and punch harder. 

Dunno who said this, but the saying goes by that, “a 9 mm will only kill the body, but the .45 ACP kills the soul”. That is pretty much the reality when you compare these two cartridges. I’m not talking about precision headshots, but hitting something or somebody with a .45 Auto on any spot will always hurt more. 

9mm vs 45: Use Cases & Effective Range

After elaborating through all that technical data, let us look upon the best use cases to understand what either of these rounds is good at. 

Maximum Effective Range

Although both these bullets can fly out to more than a mile and still be lethal to some extent. The U.S Army manual states an effective range of 9mm to be 50 meters (55 yards). Whereas a .45 ACP round fired from an M1911 A1 pistol is 120 meters (131 yards). 

The 9 mm is a flatter shooting cartridge, and with its lighter recoil, the handgun becomes more manageable when taking consecutive shots. The .45 ACP has a longer effective range due to the energy it carries, however, the shooter has to be extremely well trained to be effective at that distance. Not everyone shoots like Jerry Miculek!

CCW and EDC

As far as concealed carry or everyday carry is concerned, it is 100% personal preference. Each of these cartridges has its advantages, but it sums up to what you are more comfortable with. The 9 mm offers you to carry compact pistols, more rounds in a similar-sized magazine, and very controllable recoil. 

The .45 is a preferable choice for purists who do not want to trade ammo capacity for hard-hitting power and are more sure about their aim and training. 

Active Duty or Tactical

The .45 ACP has been one of the longest-serving sidearm rounds for the U.S Military. Whereas, the 9 mm was adopted in the ’80s and is now used by the NATO forces and most police departments around the globe. 

Additionally, the 9 mm is more prone to easily stopping and if it does hit a bystander, the chances of fatal damage are comparatively lesser. Plus, the extra ammo advantage can be crucial in an SHTF situation. 9 mm will also be a great choice for a survivalist or prepper gun due to the wide popularity of ammo. 

Competitions

9 mm pistols are unarguably more preferred for competitions compared to .45 ACP. Again, the type of competition and personal preference are the important factors that come into play. 

9mm vs 45: Costs, Availability, & Compatibility

Comparing the availability and compatibility factors for these rounds will help you decide if one is more feasible than the other. 

Readily Available but Different Pricing

The 9 mm is an abundant round on the market shelves, which also makes it the most bought and sold handgun ammunition. So when the Covid-19 pandemic struck, panic buyers stockpiled ammo and the prices skyrocketed. There are literally a ton of manufacturers making the 9 mm and since it is also a NATO round, there is seldom going to be a scarcity. Prices for 9 mm ammo are relatively cheap and good ammo can be found for as low as 20 cents per round. 

The .45 ACP has a slightly lesser demand, and the bigger size (more metal) which make it a tad pricey compared to the 9 mm. However, it is easily available on the market for as low as 55 cents per round. 

Versatile vs Traditional 

The 9 mm and .45 ACP were invented at about the same time in history, but the 9 mm came out to be a more versatile cartridge due to its controllability and size. The .45 ACP is more of a ‘purist’s cartridge’. People who like the old-fashioned way and do not mind some extra recoil or lesser ammo capacity. 

The 9 mm has a ton of handgun options, with a lot of them being very customizable, like the AR 9 mm pistol. 

Bottom Line

The 9 mm and .45 ACP were both developed more than a century ago and have proved their mettle during the Great War and any other conflicts. The 9 mm is a slightly smaller diameter and lighter bullet loaded at high pressures which offers amazing controllability and higher ammo capacity in double/single stack normal sized magazines. 

The .45 ACP is a more hard hitting round with a bigger diameter bullet and heavier bullets for a larger wound cavity. It has been a popular military sidearm round and is useful for home defense and everyday carry. 

As far as picking either of these is concerned, it depends upon personal preferences. A versatile approach will suit the 9 mm, whereas purists will adore the .45 ACP.