10mm vs 45: Which Caliber Is Best?

10mm vs 45: Which Caliber Is Best?

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Mathew R Reed
August 26, 2021
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One of the biggest choices a firearm owner will have to make is what handgun caliber to go with.

For those that know they want something big-bore, auto-loading, and serious, two names that continue to come up are the 10mm and 45 ACP.

Which is best, the 10mm or 45? The 10mm and .45 ACP rounds both have similar physical sizes in height and width and are commonly compared as two big bore calibers.

However, the 10mm round is generally considered the faster of the two when speed is necessary and the 45 has better expansion qualities and can usually do more damage, so they tend to even out.

The only true tell of which is a better cartridge is what the shooter prefers and what purpose they intend on using it for, as everyone has different requirements.

With that in mind, we’ll weigh up the .45 ACP and 10mm rounds in power, accuracy, and range to help you reach a conclusion and figure out which of the big bore calibers is the best for you.

The 10mm Explained

The 10mm Explained

The 10mm Auto is a semi-automatic pistol cartridge that first came to be in 1983, making it one of the more modern popular calibers.

A US Marine, Jeff Cooper, used the caliber with a Bren Ten pistol and evolved years later as it was eventually produced by Swedish ammunition manufacturer FFV Norma AB.

The 10mm rose to fame when it was chosen by the FBI as one of their favored ammunitions but after some use, they found that it had too much recoil for their officers to get a handle on during training.

From there, a shorter 10mm was developed, also known as the .40 S&W, offering a more compact but seriously powerful alternative.

Physically, the 10x25mm cartridge is known for producing more energy than a standard .357 Magnum load and is rated as a high-velocity option. 

The versatility of this round and its absolute power make it a good choice for everything from a home defense weapon to a backwood hunting companion.

The .45 Explained

The .45 Explained

The .45 Automatic Colt Pistol, also known as the .45 ACP and 45 Auto, was designed by the legendary John Browning in 1904.

Although originally made for the Colt semi-automatic pistol, this rimless straight-walled round would become the standard fort he M1911 pistol by Colt, and used for military purposes because of its incredible stopping power.

What sets the .45 apart is that it’s powerful, somewhat slow in speed, but with a relatively low chamber pressure when compared to others like the 9mm and .40 S&W.

Although most of the military no longer uses it as their standard round, the .45 ACP is still popular as a self-defense weapon and for large-caliber sport shooting and has a reputation for long service life.

The measurements of the .45 are 11.43 x 23mm and it comes in various specialty rounds, each with different weights and performance levels, to suit just about any setting you want.

As a combat pistol cartridge, it’s highly regarded for its excellent stopping power, manageable recoil, and expert levels of accuracy, even if it’s considered slow-moving when compared to other semi-auto rounds.

How They Compare in Power

How They Compare in Power

The .45 ACP is known as a slow-moving but good-sized bullet for a semi-automatic, and it delivers about 350-foot pounds of energy when used with a 230-grain bullet.

The 10mm offers far more power with between 600 and 700-foot pounds possible with a 180-grain bullet, making it the more serious contender in power.

Where the 10mm earns some points is its versatility and how you can use it in all types of settings, which invariably affects how much power you’ll harness from it.

If you only want to take it to target practice, you can load it with a lighter bullet, otherwise, go all out with a heavy hitter if you’re taking it into the woods for a spot of hunting.

This type of versatility isn’t something that the .45 ACP has going for it, unfortunately.

The purpose you’re using the gun for and how much power you need should also be considered, and given most people are looking for a CCW these days, the .45 ACP is the best bet.

This is because a 10mm caliber in a compact handgun can be hard to manage, not to mention it’s difficult to find many good pocket handguns chambered for it, so having the most power doesn’t always make a winner.

Accuracy and Range

Accuracy and Range

If accuracy is your priority when looking for the right handgun, you’ll be pleased to know that both the .45 ACP and 10mm offer it.

The .45 ACP is a highly accurate round and is commonly used for target practice because of its precision, and the 10mm offers a lot of power but with manageable recoil which can help with accuracy on multiple shots.

These two big-bore rounds are powerful enough to penetrate, but they differ somewhat in the speeds it takes to get them there. 

The .45 ACP is the slower of the two, rating around 830 feet per second with a 230-grain bullet, even if it does make a decent hit.

The 10mm can travel at least 1,000 feet per second, and often much more, so it has a huge advantage on the .45 in this regard.

Can You Use Them Interchangeably?

Can You Use Them Interchangeably?

Although considered two big bore calibers, it’s not possible to use a .45 ACP in a 10mm chambered firearm, or vice versa.

Some firearm owners will tell you they’ve done so before without a problem, but unless you want to pose a serious risk to yourself and your weapon, we advise against it.

The key reason that these two rounds aren’t interchangeable is because of their different size, even if they look so similar at first glance.

The 10mm comes in a longer case but with a shorter bullet, and inside of the .45 ACP is a larger projectile.

The diameter of the 10mm is .4 inches versus the slightly larger .45 that measures .451 inches. The length of them is also different with the .45 ACP being just a fraction shorter.

In addition to being differently sized, their power capabilities are also unique which makes it hard to interchange them between weapons.

The 10mm will generate over 1.5 times pressure in the chamber so attempting to place something this powerful in a gun chambered for a .45 ACP could end up doing some serious damage.

The Big Bore Winner

There’s no right or wrong answer when it comes to choosing the right caliber, so it’s up to you to think about what you prioritize from one of these big-bore rounds to get the right fit.

For hunting and similar use, we recommend the 10mm, but for a multipurpose caliber that’s better for self-defense, the 45 ACP is the way to go.

Related Questions

The caliber of a handgun can sometimes be more important than the handgun itself, so learning the basics of the different types of rounds and what they all mean is key for any firearm owner.

To help you out, we’ve got some FAQs and expert answers about calibers and guns, that will make it easier to tell them apart.

What Does a Caliber Mean?

The caliber is a measurement of the bore of a gun barrel, specifically the internal diameter of it, and all firearms will be chambered to a specific caliber size.

This measurement is usually recorded in inches or millimeters, like 9mm or .45, and it means that any cartridge that’s placed into the firearm must correlate with the caliber of the gun.

How Do I Tell the Caliber of My Gun?

All guns are chambered in specific calibers which relate to the measurement of the diameter of the gun barrel’s bore, and you must choose rounds that correlate with the chambering.

Depending on the type of gun, you may find the number of the caliber stamped somewhere on it, and usually below the breechblock or stamped on the side of the barrel, but if you’re unsure, you should take it to a gunsmith for clarification.

Which Caliber Handgun is Best for Self Defense?

If you’re purchasing a handgun for self-defense, the most popular calibers for chambering are 9mm, .380 ACP, 357 Mag, and .40 S&W.

The best approach is to test out various calibers and handguns to find one that you’re comfortable firing and which one has adequate power for this type of use.

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Mathew R Reed

Mathew R Reed is a professional gun seller who runs a dedicated gun store in the suburbs of Oakland, CA. A hardcore hunting enthusiast since childhood, Reed has ample experience with guns and accessories. He is the founder of ArmorHoldings.com and creates some of the most helpful gun-buying guides and explainers. If not in the gun shop, you can find him on the nearest hiking trail or nearby hunting spot.