IF .45 ACP AND 9MM HELPED WIN TWO WORLD WARS, HOW MANY COULD 10MM WIN?

The debate between 9mm and 10mm has become one of the more popular questions in firearms these days, especially among newer shooters who aren’t clear on the differences, or at least on how much those differences matter. 

Let’s take a close look at these two rounds and see what each one really excels at and how to choose between the two for different needs and applications. 

BALLISTICS

Ballistically, these rounds are very different, despite having a similar diameter. 10mm has a case capacity of 24.1 grains and 9mm has a capacity of just 13.3, and that translates into 50-100% more energy at the muzzle for common 10mm loadings.

This, in turn, leads to less vertical drop at longer ranges, which makes the 10mm a very flat-shooting round. It also gives the 10mm an advantage in penetration. 

On the velocity front, 9mm makes up some ground and stays relatively close to 10mm all the way out to 50 yards, where 10mm starts to noticeably improve in terms of maintaining velocity. That said, this is getting outside of handgun ranges, so it only really matters for pistol-caliber carbines.

Overall, 10mm is superior in a lot of ways, but it has some downsides that make it less than practical for a lot of applications, which we’ll get into later.

STOPPING POWER

When we say “stopping power” we’re saying it as a catch-all term to describe the effect of a cartridge on a living target, be it a wild animal or human. This is a combination of kinetic energy, velocity, bullet design, and penetration.

In terms of carrying the weapon for self-defense or hunting, this is a huge part of the equation and something that should definitely be considered.

You might think that 10mm would be the hands-down winner here, but the results are actually a bit muddy. It really depends on the ammo you choose, but 10mm will offer you a higher upper limit in terms of energy and velocity. At the upper end, 10mm factory ammo can be found in 200gr bullets moving at 1110+ FPS for over 500 ft.lb of energy at the muzzle, but also 32”+ of penetration. 

A more “normal” loading for defensive 10mm is 180gr moving at around 1,000 FPS with 400 ft.lb of energy and 16” of penetration.

“Normal” defensive 9mm commonly sits at around 124gr going 1050 FPS with 18” of penetration and 300 ft.lb of energy.

But you can also get factory ammo 9mm with a +P+ loading that slings 124gr at 1200FPS for 400 ft.lb energy and 21” of penetration.

Where the 10mm does clearly shine is in penetration against larger targets. No, I don’t mean a particularly chubby burglar, I mean like a wild animal. Think bears, boars, and xenomorphs.

With a heavier bullet, greater velocity, and a flatter overall trajectory, 10mm makes much more sense for hunting or a sidearm in bear country, especially loaded with hardcast or solid copper ammo.

RECOIL

As you’d probably expect, recoil on the 10mm is considerably more stout than 9mm. Your average 9mm will have about 4.5 ft-lbs of recoil energy in a standard loading, while a 10mm will have almost triple that at 12.85 ft-lbs of energy.

In a handgun, this difference is significant and is one of the main reasons the 10mm never took off. It was adopted by the FBI, but it was discovered that around 90% of FBI agents shot considerably better with 9mm and weren’t reliably able to deal with 10mms recoil. 

The intense recoil made follow-up shots too inconsistent, especially at longer ranges, and eventually, the FBI scrapped the 10mm sidearm and moved on to the 9mm. 

9mm is much easier to shoot rapidly, which is a key factor for self-defense, as well as competition. 10mm is larger and penetrates more, yes, but two (or more) 9mm rounds stacked on top of each other will have a far greater effect on the target than a single 10mm. 

AVAILABLE FIREARMS

10mm, especially since the FBI gave up on it, has become a bit of a niche round. Because of this, only a few companies are regularly making handguns for it in the US. S&W, Glock, Tanfoglio, CZ, and a few others each have one or two models chambered in 10mm.

Contrast this with 9mm where if the company makes handguns, then they make 9mm handguns. Most handgun makers have several models available and several variants on those models.

Seriously, it would take more space than this article’s length to list all of the 9mm handguns available just in the United States. And that’s not including the pistol caliber carbines, of which there are also a staggering amount.

On the 10mm side of things, there are maybe a dozen handguns out there worth owning, and I can count on one hand with fingers left over the number of carbine-style firearms. If you’re looking for variety and choice, the 9mm is definitely the way to go.

COST

10mm is about 2x to 3x the cost of 9mm when it comes to range ammo, and still about double the cost when it comes to serious hunting or self-defense uses. 

There’s not much else to say on this one. If cost is a factor or you’re shooting high volumes, 9mm is the winner, hands down. 

APPLICATIONS

Carry

When it comes to carry, 9mm is king and likely will be for decades to come, or until we switch to lasers and railguns. It’s the most popular handgun round on the planet, is used by most Western military and federal law enforcement forces, and has a proven track record going back over 120 years.

10mm is certainly viable as a carry gun, but the size of 10mm firearms coupled with the increased recoil makes it less than ideal, as does the reduced capacity. Modern tactical doctrine prefers multiple rounds on target over one large round, and a 9mm definitely excels there. 

Home Defense

In terms of home defense, things get a little bit murkier, but we’re still going to side with the 9mm here. The greater capacity and ease of shooting make the 9mm better against a human attacker, and there’s less risk of a round going through a wall and striking a bystander.

Where you might be better off with a 10mm out in more rural areas, particularly if you have livestock and might have to deal with predators. Dealing with large animals is something that 10mm definitely does better than 9mm, and it has better performance at long ranges as well.

Plus, the fact that your nearest neighbor is likely to be at least a quarter mile away makes the risk of overpenetration being an issue much lower.

Hunting

For hunting, 10mm is definitely the way to go. It shoots further, flatter, and penetrates deeper when it gets where it's going. Recoil and capacity aren’t really a factor when you’re hunting, so the two biggest downsides of 10mm are mitigated here.

As a sidearm in bear country, 10mm is also the definite winner due to the much deeper penetration, especially with heavier hardcast bullets.

If you’re planning to shoot an animal, 10mm is just better.

Sport/Target Shooting

If you’re competing or just plinking at the range, unless you want a beefy gun for some subjective, emotional reason (like the fact that heavy recoil is fun sometimes in a non-serious context) then 9mm is definitely the king here.

Recoil is lower, capacity is higher, and ammunition is much cheaper, so there’s really no reason to choose 10mm over 9mm unless you’re shooting in a sport that takes power factor into account, and then you’re typically always better off with .45 ACP anyway. 

Still, 10mm is fun to shoot steel with at longer ranges and can be a nice training tool as well. If you can handle 10mm recoil well, you can definitely handle 9mm recoil with ease, so think of it like a weight vest for runners but for your recoil control skills with a handgun.

Overall though, 9mm is going to be the more effective and economical option for 99% of people. 

LOOSE ROUNDS

Even in less-than-ideal applications, you won’t go super wrong with either cartridge. These are proven rounds that are as good as their shooter. 

While 9mm might be the overall king of do-all pistol calibers, 10mm still has a strong place in the world and a devoted fan base.

READY FOR MORE?

• Best 10mm Glocks: Subcompact To Full-Sized
• Best 10mm Ammo Buyer’s Guide [Self-Defense, Hunting, & More]
• 9x19mm Parabellum Vs. .380 ACP: Best Carry Caliber?
• 9mm Vs. .45 ACP: Let’s Talk About It

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