10mm vs 9mm: Does 1mm Make a Difference For Your Self-Defense Handgun?

When it comes to self-defense, many shooters hold to the belief that you should shoot the caliber that has the best ballistics and the most stopping power that you can handle. These shooters like to favor a larger caliber bullet, such as the 10mm Auto.

Other shooters believe that the ideal defense round should be lightweight and low recoil, allowing for accurate and quick follow-up shots as modern jacketed hollow points (JHP) have made the caliber debate moot. These are typically your 9mm Luger concealed carry permit holders.

The 9mm vs 10mm caliber debate is an interesting one as these two handgun rounds are extremely different from each other, despite their bullet diameter only being separated by 1mm. And it begs the question, is bigger actually better when it comes to self-defense?

In this article, we will compare the 9mm Luger and the 10mm Auto under the auspices of determining which round will be the better choice for personal defense.

What’s the Difference Between 9mm and 10mm?

When new shooters first hear about the 9mm Luger and the 10mm Auto, they often think that they are very similar cartridges. I mean how much difference can 1mm make?

Well, the answer is: Quite A Bit!

Sure, the bullet diameter is only 1mm different, but the bullet weight, muzzle velocity, and ft-lbs of energy are considerably different when comparing 10mm vs 9mm.

So, when you’re loading up your favorite semi-auto, which one do you go for? Do you go for your trusty Glock 19 or is a Glock 20 your go-to personal defense handgun?

In the next few sections, we will break down the differences between the 10mm Auto and the 9mm Luger to give you a better idea of which handgun caliber will be best for your needs.

Case Specs

Looking at the case spec chart, we see that the 9mm Luger and the 10mm Auto are extremely different.

The first thing to note is that the 10mm fires a 40-caliber bullet (0.401” bullet diameter) while the 9mm Luger fires a smaller, 9mm bullet (0.355” bullet diameter). Furthermore, the case capacity of the 10mm round is just short of double that of the 9mm, meaning that more gunpowder can fit into the 10mm allowing it to fire heavier bullets at a higher muzzle velocity.

Simply put, the 10mm round is bigger in every category compared to the 9mm Luger. With the large case comes higher pressure, velocity, ft-lbs of energy, and recoil.

All those specs lead to the biggest argument for the need for 10mm ammo, Stopping Power which we will cover in the next section.

Stopping Power

Stopping Power is one of those ubiquitous terms that gets thrown around gun store cases and internet gun forums all the time. It cannot be quantified as it is the concept of how effective a bullet is at stopping a threat.

Proponents of the 10mm round will point to the fact that it is a larger caliber, shoots heavier bullets at higher speeds and with increased muzzle energy. In theory, the bullets should leave a wider permanent wound channel and therefore cause increased blood loss if a critical organ is not damaged.

However, with modern hollow points, the gap between handgun calibers has been closed significantly when it comes to permanent wound channels.

On average, a 10mm JHP round will expand between 50-100% of its starting diameter. However, the same can be said for the 9mm Luger as well. So, if we assume maximum expansion between the 10mm vs 9mm, we are talking about 0.8” vs 0.7”. That’s not exactly a huge difference.

All modern personal defense ammo should expand with good reliability and repeatability through heavy clothing. These hollow points include the Hornady XTP, Remington Golden Saber, Speer Gold Dot, Winchester Ranger-T, and Underwood Jacketed Hollow point ammo.

FBI ballistic gel data suggests that penetration for jacketed hollow point ammo is almost identical for 10mm and 9mm ammo.

If the permanent wound cavity is similar between 9mm vs 10mm, then what is the difference?

There is some suggestion that the kinetic energy transfer that the target receives can somehow incapacitate the target or remove their will to fight. This is one of the primary arguments that proponents of the 357 SIG use for justifying their choice over 9mm.

There is a significant difference in terms of kinetic energy between the 10mm Auto and 9mm Luger, with the 10mm delivering almost double the ft-lbs of energy at the muzzle.

However, the kinetic energy transfer argument cannot be quantified, since the “will to fight” will be different between bad guys depending on multiple factors, including any illicit substances they have in their system (I’m looking at your Mr. PCP user).

There’s no doubt that the 10mm round will “hit harder” but does this really stop an attacker? Supporters of the 10mm will say yes, 9mm fanboys (and girls) will say that shot placement is more important.

The final potential difference is the size of the temporary wound cavity which occurs when a bullet impacts soft tissue. Sometimes referred to as a stretch cavity, the temporary wound cavity is caused by the rapid transfer of energy to the target from the bullet impact.

Highspeed camera footage clearly shows the 10mm Auto producing a larger temporary wound cavity than the 9mm. There are some theories that this temporary wound cavity can cause additional tearing/shredding of soft tissue in the target and therefore increase blood loss.

This is referred to as hydrostatic shock and is one of the primary reasons for the effectiveness of the 5.56 NATO (a lighter bullet going at ridiculously high velocity).

However, many ballisticians point to the fact that handgun bullets simply do not travel fast enough to cause sufficient hydrostatic shock to cause any permanent damage. So, we are still left with the question of does any of this matter? Does the kinetic energy dump aid in stopping a bad guy or is shot placement all that matters?

There may be other forces involved here that cannot be calculated or quantified by ballistic gel, and as I’m not willing to sign up to get tagged by a 10mm nor a 9mm and share my feelings on the matter, I think the topic of Stopping Power will remain unknown with current data.

However, as the 10mm has about double the kinetic energy of the 9mm Luger, we will give the edge in Stopping Power to the 10mm with a bit of an asterisk.

Recoil

If there was controversy in terms of Stopping Power in the section above, Recoil is going to be considerably more cut-and-dry.

As we mentioned earlier, the FBI moved away from the 10mm round as the heavy recoil was simply too much for agents to handle and maintain quick follow-up shots.

For your standard 10mm self-defense loads, shooters will have to endure recoil in the range of 10-12 ft-lbs of punishment to their wrists. In contrast, 9mm shooters will only have to fight off 4 to 8 ft-lbs of recoil.

Essentially, the 9mm will recoil on average 50% less making it easier for shooters to get their sights back on target for follow-up shots.

The punishing recoil of 10mm loads also causes more wear and tear on the handgun itself, requiring parts to be replaced more frequently than with a 9mm handgun.

Recoil can be mitigated somewhat by using a heavier gun, there’s no denying that an all-steel Colt Delta Elite in 10mm will have less felt recoil than a polymer-framed Glock 20.

Furthermore, bullet selection plays a role as a lighter bullet will have less recoil than a heavier bullet.

However, there is no denying that the 9mm Luger has significantly less recoil than the 10mm, making the 9mm easier to shoot and shooters can become proficient with it quicker.
The 9mm wins this one by a country mile.

Magazine Capacity

Magazine Capacity is another win for 9mm Luger as it is an overall smaller round as we saw in the Cartridge Specs section.

Your standard Glock 17 magazine can carry 17+1 rounds of 9mm Luger into battle. The Glock 20 magazine can carry 15+1 rounds of 10mm Auto, which is not insignificant by any stretch of the imagination.

However, the 9mm Luger clearly is the winner in terms of magazine capacity.

Hunting

Hunting is one category where the 10mm really shines as recoil is less important during hunting as follow-up shots are rarely used.

The 9mm and 10mm can both be used for smaller varmints with great success. However, when we start moving into feral hogs, deer, and even black bears, the 10mm is clearly the superior choice.

Its heavier bullets will be more effective at punching through thick hide and bone, making for a more humane kill. Furthermore, the flatter trajectory of the 10mm will make it the better choice for longer hunting shots.

If you’re going out into the field hunting for 4-legged critters, then the 10mm is the better choice.

Self-Defense and Concealed Carry

This one is going to be somewhat controversial, but I’m going to go out on a limb and say that the 9mm Luger is the better choice for self-defense and concealed carry. Before you start writing your email to tell me how I’m wrong, let me explain why.

For concealed carry, there’s no denying that 9mm handguns are going to be lighter than the 10mm variety. Furthermore, many shooters will opt for compact or subcompact handguns as they are easier to conceal and carry.

Now, if we are shooting smaller guns, the amount of recoil you will feel is going to be increased as there is less firearm mass to soak up that recoil impulse.

The Glock 26 subcompact 9mm is extremely popular for CCW permit holders as it has reasonable magazine capacity, is lightweight, and the recoil is manageable.

For concealed carry, a 9mm allows you to carry more ammo with a lighter handgun which means you’ll be more likely to carry it consistently.

However, one of the biggest considerations that need to be at the forefront of your mind when selecting a caliber for concealed carry is overpenetration.

Anyone who owns a firearm for personal defense needs to remember that every bullet you fire has a lawyer attached to it. This saying means that you are legally liable for every bullet you fire.
The simple fact is that accuracy will suffer during a firefight, mostly due to panic and the resulting adrenaline dump all shooters will experience. In this case, the Fight or Flight Response takes over and, as an instructor once told me, we revert to our lowest level of training and muscle memory.

Every shooter believes that they will be able to stack rounds in a tight concentric circle on the center mass of the bad guy with John Wick style precision. However, police shooting reports do not support this concept and suggest that combat accuracy is around 20-30%.

Therefore, we need to consider overpenetration as a hit to the thigh or arm is very likely to pass through the bad guy and could potentially hit an innocent bystander.

In this case, the added power of the 10mm Auto actually works against itself making it more prone to overpenetration. This is also true indoors as a 10mm can easily pass through sheetrock and external walls into your neighbor's apartment or home, potentially causing bodily harm to them (which you are liable for).

Of course, the 9mm has the potential for overpenetration as well, but overall it will be less than the 10mm.

The final point for self-defense is follow-up shots. The age-old WWII concept of one shot, one kill has long since been proven folly when it comes to handgun cartridges.

Unless your shot placement is perfect (hits in the Fatal T), it is unlikely a handgun engagement will be resolved with a single shot. Therefore, the shooter who can put more rounds on target faster will typically win the fight.

With its lower recoil and lower potential for overpenetration, the 9mm is the better option when it comes to self-defense against 2-legged bad guys.

Bear Defense

If you note the last sentence of the previous section, I referenced 2-legged bad guys.  The game changes when we get into bear country.

Overpenetration is a huge concern in urban or suburban environments, but in the woods, I want as much penetration as I can get. And if I’ve got an angry Grizzly or Boar bearing down on me, I’ll be glad to have a fully loaded Glock 20 and 15 rounds of 10mm FMJ ammo ready to go.

Predators such as bears and feral hogs are incredibly tough, they have thick hides, bones and sinew that support their large frames. This means that you need a bullet with a lot of power to punch through the skull to hit the central nervous system or crack the ribs to get to the vitals such as the heart and lungs.

A 10mm Auto is perfectly suited for this and there is a reason that the top-selling semi-auto handgun in Alaska is the Glock 20.

Can you defend yourself against a bear with 9mm? Yes, and some have.

But just because you “can” do it does not mean that it is the ideal choice. A 9mm simply does not have the energy to penetrate through thick bear skulls and bones consistently and you will need ideal shot placement to survive a bear attack with a 9mm.

The 10mm round is the clear bear cartridge of choice if you are going to use a semi-auto handgun. However, a 41 Remington Magnum or 44 Magnum revolver is often the de facto choice in bear country.

Cost and Availability

The 9mm Luger is the most popular centerfire handgun cartridge in the world, as such 9mm ammo is plentiful and easy to find. At the time of writing, 9mm ammo can be had for as cheap as $0.40/round for FMJ and around $1/round for personal defense JHP like Hornady 124 gr XTP or Winchester 115 gr Silvertip.

Buying in bulk is always smart, make sure to check out our stock of 9mm bulk ammo.

As the 10mm Auto is a larger handgun cartridge, it requires more material to produce and is, therefore, more expensive. Furthermore, it is not as popular as the 9mm, so your options for purchasing factory ammo will be fewer as fewer companies sell 10mm loads.

On average at the time of writing, 10mm ammo will run you around $0.80/round for practice FMJ ammo. Self-defense ammo will round around double that if you can find it!

As far as firearms are concerned, 9mm pistols are extremely easy to find new and used. All firearms manufacturers who sell handguns of any kind will have at least one model in 9mm (if not more).

For those who are looking to find some 10mm pistols, they are a bit harder to come by. The Glock 20 and Colt Delta Elite are the two most popular options, however, Smith and Wesson, Springfield, CZ, and Tanfoglio also have 10mm offerings.

Furthermore, a 10mm handgun is going to be a bit more expensive than a 9mm version. This is due to the fact that 10mm frames need to be beefed up a bit to handle the added abuse the 10mm cartridge imparts on the firearm.

9mm vs 10mm: Ballistics

Below our experts here at Ammo.com have compiled ballistics charts to compare the 10mm vs 9mm for several popular loads.

As we discussed earlier in the article, the defining ballistic difference between 9mm and 10mm is the massive amount of kinetic energy that 10mm packs in each round.

What we have listed below is just a sampling of each ammo type and there are considerably more loads available for each cartridge, however, this should give you a good idea of what each round is capable of.

10mm Ballistics: Chart of Average 10mm Ballistics

Note: This information comes from the manufacturer and is for informational purposes only. The actual ballistics obtained with your firearm can vary considerably from the advertised ballistics. Also, ballistics can vary from lot to lot with the same brand and type load.

9mm Ballistics: Chart of Average 9mm Luger Ballistics

Note: This information comes from the manufacturer and is for informational purposes only. The actual ballistics obtained with your firearm can vary considerably from the advertised ballistics. Also, ballistics can vary from lot to lot with the same brand and type load.

10mm Auto: The Stopping Power Champion of Lt. Col. Jeff Cooper

The 10mm Auto cartridge was initially developed by Lieutenant Colonel Jeff Cooper. Cooper designed the 10mm to have better external ballistics (muzzle velocity, effective range) than the 45 ACP and better terminal ballistics (expansion, penetration) than the 9mm Luger.

In 1983, Norma Precision improved upon Jeff Cooper’s design by increasing its power to be marketed in Dornaus & Dixon Enterprises’ new handgun, the Bren Ten (which took a page out of the CZ-75 design handbook).

The new 10mm Auto cartridge submitted by Norma was derived from the .30 Remington rifle round and had an extremely flat trajectory and high muzzle energy on par with the 357 Magnum in some loadings.

Although the Bren Ten handgun was doomed to failure due to an extremely high price tag, production delays, and eventual bankruptcy of Dornaus & Dixon, the 10mm Auto was saved by Colt and their release of the Delta Elite (a 10mm version of America’s beloved M1911 handgun) in 1987. Furthermore, the FBI adopted the 10mm Auto as their new service handgun cartridge in response to the 1986 Miami Shootout.

However, the 10mm Auto’s reign as the FBI caliber of choice was short-lived, as agents were having a hard time handling the heavy recoil that 10mm ammo imparted upon their flimsy federal wrists. A reduced power 10mm load was constructed and found to be acceptable for use in the field.

Smith and Wesson quickly started working on the “10mm Lite”, as some agents referred to it, and quickly discovered they could chop 3mm off the overall case length and still achieve the same ballistic results.

And in 1990, the 40 Smith and Wesson (40 S&W) was born from the 10mm Auto.
The 40 S&W saw a quick rise in popularity with law enforcement since its debut, but it has recently fallen out of favor and many departments are switching back to the 9mm Luger (including the FBI).

Despite the 40 S&W falling from law enforcement graces in favor of a 9mm Glock sidearm, the 10mm Auto still has a devoted fanbase in the shooting community and many firearms manufacturers produce 10mm pistols like Kimber, Smith and Wesson, Springfield, Glock, and Ruger.

Standard 10mm ammo will come in a bullet weight range of 165, 180, and 200 grain projectiles. Specialty 10mm loads can be found as low as 60 grains and as high as 220 grains. The 180-grain loading is the most popular 10mm ammo and an average Federal 10mm 180gr FMJ round will have a muzzle velocity of 1,300 fps and muzzle energy of 708 ft-lbs. SAAMI specs indicate that the max pressure for 10mm ammo is 37,500 psi.

To put these 10mm ballistics into context, 10mm ammo has more ft-lbs of energy and fps of velocity at 50 yards than the 45 ACP has at the muzzle. That’s some serious stopping power!

Hotter 10mm loads can achieve even more impressive results. Take for example the 155 gr Underwood XTP-JHP departing the muzzle at 1,500 fps and pounding the target with approximately 775 ft-lbs of force. These numbers exceed that of the gold standard for stopping power: the 125 grain JHP .357 Magnum round. SAAMI specs stipulate that the maximum case pressure for the 10mm is 37,500 psi.

The no denying that the 10mm Auto is an extremely capable defense round, but it has also been the sire of other handgun rounds. The 40 S&W was the first, however, the 357 SIG and 9x25mm Dillon are both necked down versions of 10mm Auto.

The 10mm Auto is extremely versatile and affords shooters with 357 Magnum power in a semi-auto handgun. This makes it a very potent home defense round and allows for deep penetration even when using jacketed hollow points (JHP).

But does this mean that the 9mm Luger is an inferior round and you should go grab a Glock 20 today? Not necessarily! Let’s look at the history of the 9mm before we jump to that conclusion.

9mm Luger: The Austrian Concealed Carry Staple

The 9x19mm Luger was designed by the Austrian gunsmith Georg Luger in 1901. Luger derived the 9mm Parabellum from his previous design, the 7.65x21mm Parabellum.

In 1903 he presented the 9mm Luger to the US military for consideration at the Springfield Arsenal and was in competition with Browning and the 45 ACP. The 9mm was not adopted by the US military until much later and was instead picked up by the German Imperial Navy and Army in 1904 and 1908, respectively.

The 9x19mm Luger is also referred to as the 9x19mm, 9mm Parabellum, or simply the 9mm.  SAAMI specs list the maximum pressure for 9mm at 35,000 psi and standard 115 grain FMJ ammo will have an average muzzle velocity of 1180 fps and a muzzle energy of 355 foot-pounds.

After World War I and through World War II, 9mm ammo became one of the most popular handgun cartridges in Europe for both military and law enforcement. However, the United States was late to the party as it clung to the idiom, “Bigger Bullets are Better” and our beloved 45 ACP until the 1980s with the adoption of the Beretta M9 Service Pistol by the US Army.

The popularity of the 9mm Luger really exploded in the United States during the ’80s and '90s with the introduction of extremely reliable semi-auto pistols, such as the Glock 17, the Sig Sauer P226, and more recently the Springfield XD and the Smith and Wesson M&P.

Fervor for the 9mm round has only been bolstered by the U.S. military’s adoption of the Sig Sauer P320 as the new standard-issue sidearm for military personnel.

The 9mm has become synonymous with law enforcement and home defense for its high magazine capacity, stopping power using jacketed hollow point ammo (JHP), and low overall cost per round.

9mm pistols are extremely easy to come by and are relatively inexpensive as all major firearms manufacturers carry some offering for the 9mm cartridge: Glock, Smith and Wesson, Sig Sauer, Kimber, Springfield, Remington, Ruger, and Taurus, just to name a few!

It has truly become the everyday carry (EDC) handgun of choice if you don’t want to carry something more chunky and snappier like a 357 Magnum. And with advancements in hollow point technology, the 9mm has solidified itself as the self-defense ammo of choice for the military, law enforcement, and the civilian concealed carry permit holder.

But which handgun cartridge is the best choice for you? Let’s compare the 9mm vs 10mm!

10mm vs 9mm: Final Shots

When it comes to comparing handgun rounds, it is difficult to crown a winner as each cartridge has its advantages and disadvantages.

The 10mm Auto is a powerful handgun cartridge that was developed to bridge the gap between the 9mm Luger and the 45 ACP. It imparts massive kinetic energy into its targets at the cost of punishing recoil, increased handgun wear, and the increased potential for overpenetration.

The 10mm can fire larger caliber and heavier bullets than the 9mm at considerably higher muzzle velocities, making it an extremely powerful cartridge.

Although the FBI moved away from the 10mm in favor of the 40 S&W, the 10mm Auto is an excellent choice for hunting deer, hogs, and even bear as its superior penetration is ideal for taking these larger game animals.

The 9mm Luger has quickly become the most popular handgun cartridge in the shooting world due to its low recoil, higher magazine capacity, and ease of handling. Many shooters report being more accurate shooting a 9mm than they are with other cartridges, and this is mainly due to the reduced recoil impulse that the 9mm offers.

The 9mm is the obvious choice for self-defense for the reasons stated above and the law enforcement community seems to agree, as many departments and agencies are transitioning their duty sidearms back to 9mm Luger.

But does this mean that you should only buy a 10mm if you like hunting? Definitely not!

If a 10mm is on your bucket list or you’re just a recoil junkie, then you grab that Glock 20 or Delta Elite and you carry that handgun with the pride that comes knowing you have enough kinetic energy to stop a bear on your hip.

Just be aware of the liabilities that come with carrying such a heavy-hitting handgun cartridge. In any self-defense situation, always be aware of your backstop and make sure you consistently practice with your EDC handgun so that you can put rounds on target accurately under stress.

So long as you do that, carry what you shoot best and flex those 2A Rights!