Tell a normie that you’re debating between carrying a Glock 20 or a Glock 21, and they’re liable to look askance at you. “Why do you care so much about one number?” the normie might ask. “Surely it’s not worth getting all bent out of shape over?”
“Au contraire, mes ami,” you would counter. “I’m not debating between handguns. I’m debating between handgun cartridges. My dilemma is thus: Do I carry a pistol chambered for 45 Automatic Colt Pistol (ACP, or Auto), which was the U.S. military’s standard sidearm cartridge from 1911 until 1985? Or do I carry one chambered for the stronger 10mm Auto, which made its debut in 1983?”
That’s the very dilemma I set out to answer in this article.
10mm or 45 ACP
Not “Better” – “Different”
This article’s purpose isn’t to declare which is the “better cartridge.” No such thing exists. The 10mm may be powerful, but power isn’t everything. For example, the 50 BMG is stronger than either of these rounds, yet you’d hardly want to carry its ~30-pound rifle for personal protection (unless you live on Skull Island). And because it is more powerful, the 10mm’s performance is accompanied by something most consider to be undesirable; namely, heavier recoil.
Let us also observe the importance of skill. For example, imagine two men. One is an Iraq War veteran wielding the same bolt-action 22 LR rifle his grandpappy harvested squirrels with during the Great Depression. The other is a total nincompoop who has never actually fired his pieced out DDM4. Now, which of these characters do you think would defend himself more effectively?
In summary, we can objectively compare the 45 ACP and 10mm to a fare-thee-well – indeed, we are about to do just that – but we cannot determine which is actually better for you. Only your own personal experience and circumstances can do that.
45 ACP vs. 10mm: Physical Dimensions
Comparing a couple of cartridges begins with placing them side by side. Do that and you’d see that 45 ACP ammo is much larger. Its bullet is 0.0515” wider in diameter. Its case neck and base are both about 0.05” wider as well. The 10mm’s case may be 0.094” longer, but the round’s overall length is 0.015″ shorter.
| (SAAMI) | 10mm | 45 ACP |
|---|---|---|
| Parent case | 30 Remington | N/A |
| Case type | Rimless, straight | Rimless, straight |
| Bullet diameter | .4005 in | .452 in |
| Neck diameter | .423 in | .473 in |
| Base diameter | .425 in | .476 in |
| Rim diameter | .425 in | .480 in |
| Rim thickness | .055 in | .049 in |
| Case length | .992 in | .898 in |
| Overall length | 1.260 in | 1.275 in |
| Case capacity | 24.1 gr H2O | 25-27.4 gr H2O |
| Maximum pressure | 37,500 psi | 21,000 psi |
The higher-powered 10mm’s shorter length makes sense in light of its narrower caliber. The .40 cal 10mm was initially developed to fire a 180 grain bullet. In contrast, the broader .45 cal 45 ACP was originally standardized with a 230 grain bullet: almost 28% heavier. The 45 ACP’s more massive and voluminous bullet necessitates the round’s overall greater dimensions.
45 ACP may be larger, but the 10mm has something it hasn’t: around 70 more years’ worth of technological advancement behind its design. The 45 ACP was certainly advanced for its time, as it was almost as powerful as the 45 Colt revolver round it was developed to replace, despite being much shorter. But thanks to the more potent propellant it’s designed to accommodate, the 10mm is able to generate higher chamber pressures. Its maximum pressure is 78% higher!
Capacity Considerations
We’ll examine the effects of the 10mm’s higher chamber pressure and (usually) lighter bullets in a moment. Before we do, let’s touch on the subject of capacity. Because they are narrower in diameter, more 10mm cartridges can fit into the same amount of space as 45 ACP ones can. For reference, a 10mm G20 Gen4 with a standard magazine measures 5.51” high and has a shot capacity of 15. Despite sharing the same height, a 45 ACP G21 Gen4 has a standard magazine capacity of 13.
Obviously, different handguns have different standard capacities (I say “standard” because all bets are off once the extended mags come out). The M1911’s single-stack magazine holds a mere seven rounds. Taking variation into account, it’s reasonable to expect a lower capacity if you choose a 45 ACP pistol over a 10mm alternative with roughly the same dimensions. That’s important to take into consideration. No one ever wished they had less ammo during a life-threatening altercation.
45 ACP vs. 10mm: Ballistics
To recap, the 10mm usually fires a lighter bullet at a higher velocity. Its standard 180 grain projectile hits a muzzle velocity of 1,200-1,300 fps; substantially zippier than the 45 ACP’s standard 230 grain bullet, which typically achieves 825-900 fps muzzle velocity (both out of a 5” test barrel).
To illustrate the differences between the two rounds’ performance, we attempted to divide them into three categories: lightweight (170 vs. 185 grains), middleweight (180 vs. 200 grains), and heavyweight (200 vs. 230 grains). These are admittedly imperfect, non-apples-to-apples comparisons, but they illustrate the differences between the rounds’ ballistic performance all the same.
Light & Middleweight Bullets
| PMC 10mm 170gr JHP; 5" bbl; 0.113 G1 BC | Winchester 10mm 180gr JHP; 5" bbl; 0.179 G1 BC | ||||||
|---|---|---|---|---|---|---|---|
| Range (yds) | Velocity (fps) | Energy (ft lbs) | Elevation (in) | Range (yds) | Velocity (fps) | Energy (ft lbs) | Elevation (in) |
| 0 | 1200 | 544 | -0.19 | 0 | 1235 | 610 | -0.19 |
| 25 | 1117 | 471 | 0.79 | 25 | 1176 | 552 | 0.7 |
| 50 | 1052 | 418 | 0.01 | 50 | 1125 | 506 | 0.01 |
| 75 | 1001 | 378 | -2.73 | 75 | 1081 | 467 | -2.4 |
| 100 | 959 | 347 | -7.63 | 100 | 1044 | 435 | -6.67 |
| 125 | 923 | 321 | -14.9 | 125 | 1011 | 409 | -12.93 |
| PMC 45 ACP 185gr JHP; 5" bbl; 0.098 G1 BC | Winchester 45 ACP 200gr JHP; 5" bbl; 0.165 G1 BC | ||||||
| Range (yds) | Velocity (fps) | Energy (ft lbs) | Elevation (in) | Range (yds) | Velocity (fps) | Energy (ft lbs) | Elevation (in) |
| 0 | 900 | 333 | -0.19 | 0 | 1000 | 444 | -0.19 |
| 25 | 865 | 308 | 1.38 | 25 | 970 | 418 | 1.08 |
| 50 | 834 | 286 | 0.02 | 50 | 944 | 396 | 0.02 |
| 75 | 805 | 266 | -4.46 | 75 | 920 | 376 | -3.48 |
| 100 | 778 | 249 | -12.29 | 100 | 898 | 358 | -9.55 |
| 125 | 753 | 233 | -23.71 | 125 | 877 | 341 | -18.32 |
Heavy Bullets
| Federal 10mm 200gr JHP; 5" bbl; 0.095 G1 BC | |||
|---|---|---|---|
| Range (yds) | Velocity (fps) | Energy (ft lbs) | Elevation (in) |
| 0 | 1130 | 567 | -0.19 |
| 25 | 1051 | 491 | 0.9 |
| 50 | 992 | 437 | 0.01 |
| 75 | 944 | 396 | -3.09 |
| 100 | 903 | 362 | -8.63 |
| 125 | 867 | 334 | -16.83 |
| Federal 45 ACP 230gr JHP; 5" bbl; 0.192 G1 BC | |||
| Range (yds) | Velocity (fps) | Energy (ft lbs) | Elevation (in) |
| 0 | 900 | 414 | -0.19 |
| 25 | 882 | 397 | 1.32 |
| 50 | 865 | 382 | 0.02 |
| 75 | 849 | 368 | -4.19 |
| 100 | 833 | 354 | -11.42 |
| 125 | 818 | 342 | -21.78 |
Singling out the flatter-shooting cartridge is easy: it’s the one with supersonic (i.e. higher than 1,125 feet per second) muzzle velocity. The 10mm covers the distance between muzzle and target faster, thereby giving gravity less time to exert its constant effect on the bullet. The more ponderous 45 ACP bullet takes longer to reach its target, and it spends all of that time falling. And because its bullet is wider and less aerodynamic, the 45 ACP sheds momentum at a faster rate than the 10mm as well.
The 45 ACP exhibits steeper bullet drop. But is it less accurate? Not at all. The round’s characteristically slopier trajectory is nothing a skilled marksman can’t reflexively compensate for with his aim. Colonel Walter Walsh killed a Japanese sniper on Okinawa with one shot of his M1911 – at 90 yards. You’re not him, but most anyone could train to reliably hit targets over conventional self-defense distances, regardless of their preferred handgun cartridge.
45 ACP vs. 10mm: Stopping Power
Astute readers will have already noticed another effect of the 10mm’s higher muzzle velocity: higher striking energy. The 10mm consistently hits harder than the 45 ACP. A 200 grain 10mm round’s muzzle energy is around 28% higher than that of an analogous 45 ACP load.
Don’t interpret that the wrong way. Either of these cartridges packs more than enough punch for effective self-defense over the distances which typically separate assailants from their would-be victims. For reference, we calculated the farthest distances our six example rounds will conserve at least 260 ft lbs of kinetic energy within. (We chose that threshold because it’s a reasonable estimation of the minimum energy you would ideally want for defense.)
| 260 ft lbs (yds) | |
| PMC 10mm 170gr JHP | 205 |
| Winchester 10mm 180gr JHP | 377 |
| Federal 10mm 200gr JHP | 212 |
| PMC 45 ACP 185gr JHP | 84 |
| Winchester 45 ACP 200gr JHP | 289 |
| Federal 45 ACP 230gr JHP | 329 |
No two ways about it: the 10mm hits harder. But brute force isn’t the sole determinant of “stopping power” (largely because the term has no real definition). For example, bullet diameter also matters. The 45 ACP may not transfer as much kinetic energy to its target, but its wider bullet does tunnel a more injurious hole through soft tissue and possess a higher likelihood of striking a vital organ in the process.
At the end of the day, neither round is worth a toot if it doesn’t hit its target. That brings us to one of the largest determinants of accuracy.
45 ACP vs. 10mm: Recoil
Action; equal and opposite reaction. That’s Newton’s Third Law, and it accounts for the recoil you experience when you fire a gun.
Less recoil is always preferable, and not solely because it makes shooting more comfortable. It also causes less muzzle rise: i.e. upward jerking motion of the barrel during ignition. Muzzle rise forces the shooter to spend more time restoring his aim on target in between shots, which slows (accurate) rapid fire.
Free recoil energy is measurable so long as you know four numbers: firearm weight, bullet weight, propellant charge weight, and muzzle velocity. For the sake of comparison, let’s reasonably assume all the aforementioned 45 ACP rounds have 8 grains of powder, and all 10mm rounds have 10. Let’s also assume we’re firing two 2.5-pound handguns (approximately the same as a loaded G20 or G21).
| Recoil Energy (ft lbs) | |
|---|---|
| PMC 10mm 170gr JHP | 8.18 |
| Winchester 10mm 180gr JHP | 9.41 |
| Federal 10mm 200gr JHP | 9.66 |
| PMC 45 ACP 185gr JHP | 5.41 |
| Winchester 45 ACP 200gr JHP | 7.31 |
| Federal 45 ACP 230gr JHP | 7.74 |
Under those circumstances, even the lightest 10mm cartridge generates more recoil energy than the heaviest 45 ACP.
Felt Recoil
Our numbers don’t even tell the whole story, because recoil isn’t purely objective. People feel it. Those who have experienced it tend to describe the 10mm’s recoil as snappy (hence why it was weakened until it became the 40 S&W: an altogether different cartridge). In contrast, 45 ACP enthusiasts often extol their preferred round’s recoil for feeling more like a push than a whip crack.
Subjective takes aside, neither of these rounds has inconsequential recoil. Both kick harder than the 9mm, which is more popular than either largely for that very reason. Both can discomfort inexperienced shooters as well . But with all things being equal, the 45 ACP does have softer recoil, which can help you put more shots on target in a shorter amount of time.
45 ACP vs. 10mm: Availability and Cost
People LOVE the 45 ACP. Chalk that up to veterans’ fondness for the same types of ammo they served with, as well as the 45 ACP’s service overlapping almost three-quarters of the 20th century.
There is enormous demand for 45 ACP firearms and ammunition in the U.S. Anyplace that sells ammo stocks 45 ACP. We have offered well over 100 different kinds of 45 ACP ammo for sale over the years.
Compared to 45 ACP, 10mm is way less popular. It just hasn’t been around for as long, and it doesn’t have its competitor’s military or law enforcement pedigrees. We’ve only offered around 30 different kinds of it over the years.
We’re not suggesting 10mm ammo is rare. You’ll find 10mm ammo at our shop easily enough – if not at the sporting goods store, then definitely online, which is indisputably the better way to shop for ammo. With that said, you will limit yourself to fewer options if you choose 10mm over 45 ACP. You’ll also pay more for it, if only because factories produce it in lower quantities.
Conclusion
The 10mm and 45 ACP are two powerful semi-automatic handgun cartridges. Either is more than adequate for self-defense. The 10mm’s flatter trajectory can simplify aiming over significant distances, though neither round’s accuracy leaves anything to be desired. The 10mm’s higher striking energy increases the shooter’s odds of neutralizing the threat before harm can come of him. These advantages come at the cost of relatively higher recoil, however. The 45 ACP’s kick isn’t insubstantial, though it is widely considered to be gentler than that of the 10mm.
Remember: articles like these don’t substitute for hands-on experience. If you really want to discern which of the two rounds is better for your needs, test them out for yourself. The round you feel more comfortable and confident firing is almost always the better!
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