Over the years, the firearms world has enjoyed multiple variants of the US car culture’s “Ford vs. Chevy” debate: Back in the 1980s a lot of people argued about the “.45 ACP vs. 9mm” comparison, as the US Army transitioned from its venerable 1911 sidearm chambered in .45 ACP to the shiny new Beretta M9 in caliber 9x19mm Parabellum. Later, when the 9mm was deemed ineffective in a high-profile Miami shootout, the FBI adopted the powerful new 10mm Auto, but due to excessive recoil and muzzle blast, that was quickly “downloaded” into “10mm Lite” or “10mm FBI,” which then led to the creation of the .40 S&W cartridge and its adoption by the FBI in 1997. This led to perpetual “9mm vs. .40” debates in gun shops and internet forums.
However, with the recent resurgence in popularity of the 10mm Auto, and more firearms manufacturers offering models chambered in “the best millimeter,” along with the FBI returning to 9mm in 2017, there has been a lot of renewed interest in the comparison between the 9x19mm Parabellum (also known as 9mm Parabellum, 9mm Para, 9mm Luger, or commonly “9 millimeter”) and the 10mm Automatic (also correctly termed the 10mm Auto, and commonly known simply as the “10 millimeter”) cartridges. People may think, “How much difference could one millimeter actually make?”
Well, there’s a lot more to this comparison than simply a 1mm increase in the diameter of the projectiles. In this article, we’ll go over the basic characteristics, ballistics, differences, and purposes of these popular cartridges, and hopefully help you decide which one might be right for you and your particular intended use.
9mm ballistics
When discussing the ballistics of a particular cartridge, there are essentially two main topics to discuss: External ballistics, usually evaluated by bullet velocity, energy, and drop, and terminal ballistics, or the effect of a bullet when it impacts organic tissue (often evaluated using ballistic gel). First, let’s talk about 9mm bullet velocity in commonly available loadings.
9mm bullet velocity
The original 9mm Luger load from 1902 was an 8 gram bullet (approximately 124 grains) fired at a speed of 327 meters per second (1,073 feet per second) out of a 100mm-long barrel (a little less than 4 inches). Modern loadings can do a little better, but many “bulk” loads today produce similar numbers. In standard, non-plus-P loads, commonly available 115-grain 9mm cartridges typically produce around 1,150-1,200 fps from 4” barrels, while 124-grain bullets are usually clocking around 1,100-1,150 fps (there are some aberrations but this is a pretty good generalization).
In +P and +P+ (higher pressure) loadings from boutique manufacturers such as Underwood Ammo and Buffalo Bore, you can potentially achieve speeds of around 1,400 fps in 115 grain, 1,300 fps in 124 grain, and 1,100 fps in 147 grain 9mm from standard-length handgun barrels. If you choose to shoot +P or +P+ ammo through your gun, you assume the risks or at the very least, the increased recoil and wear to the gun. Carbines and rifles can often produce even higher velocities.
The effective range of the 9mm
Discussing the “effective range” of any cartridge is always a question of priorities and is somewhat subjective. After all, we know that for many years, manufacturers of .22LR ammo published that the bullet was potentially lethal out to one mile, and tests have shown that to be the case. But almost nobody would claim that the “effective range” of .22LR is greater than around 250 yards maximum.
The 9mm Parabellum cartridge was designed by its creator, Georg Luger, to be lethally effective out to 50 meters (164 feet). The cartridge is certainly capable of being effective at further distances, but the question becomes, how effective can the shooter be at making those longer-range hits? The G1 ballistic coefficient (BC) of most 9mm bullets varies from around 0.13 for many 115-grain bullets to 0.17 for some 147-grainers (higher BC bullets generally “fly better”). This isn’t particularly good (several semi-auto handgun cartridges offer bullets with higher BC, even the .45 ACP), and certainly isn’t close to what a well-designed rifle bullet can do, some of which have BCs of 0.83 or better.
Typically, 100 yards is at the far end of the practical limit for the vast majority of handgun shooters, and most have trouble hitting with any practical accuracy beyond about 40 yards or so. At those distances, 9mm bullets are still traveling very quickly and are absolutely capable of delivering effectively lethal energy and damage.
For example, a run-of-the-mill 9mm “ball” load of Federal American Eagle 124 grain FMJ (full metal jacket) at 100 yards has a velocity of around 960 fps, for an energy of at least 250 ft/lbs, which is certainly capable of inflicting a lethal wound.
At 200 yards with the same load, velocity has only dropped to 855 fps, and energy is 201 ft/lbs.
Even at 400 yards, velocity exceeds 680 fps, and energy is around 130 ft/lbs. For reference, the US Armed Forces reportedly said during WWII that a bullet impact of 36 ft/lbs of energy was potentially lethal. As of today, that number has been increased to 59 ft/lbs. So, if we take that number as accurate, we can see that even past 400 yards, a common 9mm bullet is still “lethal”... if you can hit anything that far away with it, which almost nobody can. In essence, the 9mm retains lethal velocity and energy farther than you can accurately shoot it, whether you are using a handgun or a rifle/carbine.
Modern 9mm Parabellum JHP (jacketed hollow point) defensive bullets perform very well in terminal ballistic/gel testing, with many loads achieving the FBI’s recommended effective penetration of between 12 and 18 inches of ballistic gel, and expanding up to .74” inches for some loads. Depending on the load, 9mm can produce up to 480 ft/lbs of muzzle energy, though the majority of typical defensive loads produce between 300-400 ft/lbs. Testing and real-life performance in shootings have demonstrated the 9mm to be a very effective defensive cartridge within common self-defense or police shooting distances.
Bullet drop of the 9mm Parabellum
Compared to other popular handgun cartridges used for similar purposes over the years, such as the .38 Special and .45 ACP, the 9mm is indeed a “flat-shooting” cartridge. Depending on the load, bullet drop at 100 yards is only about 10 to 12 inches in most common loadings, compared to around 16-24 inches for common .38 Special rounds and 16-20 inches in the common bullet weights for the .45 ACP.
Some of the lighter and/or faster 9mm loadings produce a 100-yard bullet drop of under 8 inches. Bottom line? If you’re an accurate enough shooter, the 9mm can hold its shots within a 12” plate all the way from point blank to 100 yards with no significant adjustment to the sight alignment.
10mm ballistics
The 10mm Auto was developed in the early 1980s by handgun legend Jeff Cooper and his associates John Adams, Whit Collins, and Irving Stone, by taking a .30 Remington case, cutting it to .922”, and loading it with a .40 caliber bullet. The cartridge was increased in power and formally created by Norma in 1983. Initial loadings employed a 170-grain JHP moving at 1,300 fps (for 600 ft/lbs of muzzle energy) or a 200-grain full-jacketed truncated-cone bullet at a velocity of 1,200 fps, producing 635 ft/lbs of muzzle energy, at a maximum pressure of 44,400 psi (most loads are kept at around 37,000 psi). Let’s look at modern loadings and see how some other aspects of 10mm ballistics stack up.
10mm Auto bullet velocity
As noted above, one initial 10mm Auto load fired a 200-grain bullet at 1,200 fps, which is a similar speed to standard 9mm loads firing a 115-grain bullet. However, modern ammo manufacturers like Underwood offer impressive 10mm loads, from a 100-grain bullet moving at a screaming 1,825 fps up to a 220-grain bullet going 1,200 fps. Their 165-grain load pushes a JHP bullet at a claimed 1,400 fps. Testing has shown that real-life velocities for premium ammo manufacturers such as Underwood, Buffalo Bore, and Double Tap are usually very close to published claims.
There are several excellent defensive/hunting loads for the 10mm, including Federal’s premium HST jacketed hollow-point load pushing a 200-grain bullet at an advertised 1,130 fps. Most commercial 10mm loads produce velocities between 1,000 and 1,300 fps.
It’s clear that achieving the maximum potential of the 10mm Auto cartridge requires careful handloading or selecting a premium, “boutique” ammo maker. However, with velocities that are broadly similar to the majority of 9mm loadings, the 10mm may seem like it doesn’t have much more to offer by comparison. The key here is that the 10mm achieves these velocities with bullets that are generally 40% to 90% heavier than their 9mm counterparts, translating into a lot more energy. And that brings us to the question of effective range.
The effective range of 10mm Auto
Since the 10mm case holds 24.1 grains of water (case capacity is measured in grains of water by weight) compared to the 9mm Parabellum’s 13.3 grains, 10mm Auto is capable of launching large bullets at very respectable speeds. The 10mm is often compared to the .41 Magnum, though this is not an apples-to-apples comparison, since the .41 Mag is capable of significantly more power when loaded properly. A more appropriate comparison would be to compare the 10mm to the .357 Magnum revolver cartridge, which is known to be a hard-hitter in defensive situations as well as a capable hunting round with the right loads.
The 10mm, loaded properly, can outpace the .357 Magnum in most bullet weights while maintaining semi-auto capability and capacity. Depending on the load, the 10mm can produce up to 760 ft/lbs of muzzle energy, though the majority of typical full-power defensive 10mm Auto loads produce between 600-700 ft/lbs.
As far as effective range, since the G1 ballistic coefficient of most 10mm bullets is quite similar to those offered by the 9mm, varying from around 0.13 to a bit over 0.17, one could argue that the 10mm may have a collective advantage here since there are more 10mm projectiles hovering in the 0.17 BC range, but in general, the two bullets are quite similar in how they fly. We’ve noted above that the 9mm remains quite lethal out to 400+ yards, and the 10mm, which moves at similar speeds, performs at least as well. However, the 10mm begins with significantly more energy at the muzzle, and retains more energy out to 50, 100, and 200+ yards, so it could be argued that you have a better chance of any hits you make being “effective” with the 10mm compared to the 9mm.
However, compared to the 10mm, 9mm is almost always cheaper, and in most cases, half or a third of the cost for a similar quality loading. Premium JHP 9mm ammo currently starts at about $.80/rd when you buy in bulk, while equivalent 10mm is almost always at least double the cost, starting around $1.60/rd and going up from there.
Additionally, since 9mm is the most popular chambering for defensive pistols, prices for 9mm guns have gotten relatively low and availability and choices are plentiful. 10mm, on the other hand, while experiencing a resurgence by any estimation, is still chambered in relatively few handguns. While a handgun manufacturer might offer dozens of 9mm pistol models, they might offer one in 10mm or none at all. What’s more, since 10mm is a lot more powerful, guns must necessarily be built stronger and utilize more material to handle the abuse. This means that choices are limited, and prices are almost always significantly higher if you’re looking to buy a 10mm handgun. You gotta pay to play in the 10mm world.
Hunting: the 10mm is vastly superior to the 9mm
Nobody in their right mind would recommend 9mm as an ideal hunting cartridge, though many whitetail deer and smaller game have been taken with it, where legal. This might seem silly to those who have viewed the 9mm as a range toy or self-defense caliber only, but as we’ve seen, the 9mm is capable of launching high-quality JHP bullets at speeds up to 1,400 feet per second from handguns. That’s nipping on the heels of many .357 Magnum velocities and in some cases exceeding them when comparing equivalent bullet weights, depending on the barrel length of the guns being compared. So, if a 9mm is legal for whitetail or coyote hunting in your area, and you’re a capable marksman (or woman), the 9mm can certainly do the job.
However, the 10mm Auto is undeniably superior when it comes to hunting, particularly if your quarry includes larger or tougher animals such as wild boar, bear, mule deer, elk, moose, etc. There’s a reason the Glock 20 and Glock 41 are among the most popular handguns for carry in bear country like Alaska. While people have defended themselves against bear attacks with 9mms, the big 10 is objectively a better choice, as long as you can handle the increased size of the gun and the increase in recoil. The heavier, tougher bullets available in 10mm, combined with the increase in energy, help 10mm perform much more reliably against thick-boned, tough-hided animals with lots of tissue to penetrate.
Recoil and muzzle blast: The 10mm is a handful, while the 9mm is a pussycat
Recoil can be a significant factor when you’re selecting a handgun, particularly for defense. The 9mm has much less recoil than the 10mm, typically one-half to one-third the amount (common 9mm loads produce between 4 and 8 ft/lbs of recoil energy, while common 10mm loads produce between 10-12 ft/lbs, and sometimes significantly more, depending on the load). More recoil translates to more time between effective follow-up shots, even with experienced shooters, as well as an increased potential for the shooter to develop a “flinch” that can hinder accuracy. The FBI found that the 10mm Auto was too much for about 90% of its agents, who were unable to effectively handle the larger, heavier pistols and the stout recoil produced by the full-power 10mm cartridge. The organization downloaded the 10mm to try to solve the problem, which is the primary reason for the birth of the .40 S&W (often jokingly called the “forty short and weak”) that the FBI adopted and used for the next couple of decades, before eventually switching back to 9mm as better bullets became available.
Muzzle blast of the higher-pressure 10mm loads can also be punishing, which is a factor in defensive situations where you may be inside your home and will almost certainly not be wearing ear protection.
Self-defense: Terminal ballistics are nearly identical; 9mm guns are smaller and lighter
“Any serious self-defense cartridge must start with a 4,” according to some memes and long-held beliefs. This stems from the poor performance of .38 caliber bullets against determined adversaries in the early 20th century, as well as the mythical inability of military 9mm FMJ loads to adequately stop opponents. If you’re comparing .45 ACP ball against a 9mm ball, there may be some evidence to suggest that the larger bullet might perform a little better (though the evidence is generally spotty and, truthfully, all handgun FMJ/ball ammunition performs relatively poorly as a “manstopper”). However, since the 1990s, there have been many improvements in projectiles and bullet performance in defensive calibers, and in objective comparisons of “stopping power” in real shootings with center thoracic hits, all of the popular defensive and police calibers (9mm, .357, .40, 10mm, and .45) using modern bullets have performed almost identically.
If we accept this evidence, then 9mm starts to show distinct advantages when compared to 10mm for defensive use against human threats. There has been a large number of truly small, packable 9mm CCW pistols hitting the market over the past few years, which helps the argument further. After all, if 9mm and 10mm perform basically the same against human attackers, why put up with the greatly increased cost, blast, recoil, weight, and size of a 10mm?
So, which is better, 9mm or 10mm? For plinking, target shooting, competition, and self defense, the 9mm is the winner. For bear/dangerous animal defense, hunting, or “go-big-or-go-home” blasting for fun, the big ten is the obvious choice. What would we recommend? Well, when it comes to firearms, our usual advice is, “Why not get both?”
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