The Myth of The .45 ACP

The legendary .45 ACP semiautomatic handgun: Is there any other caliber - gun combination that is so well-regarded? Why are we even bothering to question what is clearly a seasoned, battle-tested cartridge?

Well, as you'll see, with the .45 ACP, not everything is as it seems.

The .45 ACP, as is well-known, was born of a series of tests conducted in 1904 as a result of the Philippine Insurrection, popularly called the "Thompson-LaGarde Tests". Here is a fair account of the tests, and most of my discussion of the tests will be based around that article.

Most proponents of the .45 ACP and the 1911 handgun know of only the conclusions of the test, repeated here for convenience:

"the Board was of the opinion that a bullet, which will have the shock effect and stopping effect at short ranges necessary for a military pistol or revolver, should have a caliber not less than .45″

However, this conclusion was not then, and is not now, any evidence at all in the discussion of handgun calibers. As I will enumerate, the testing procedures were deeply flawed, so much so that virtually no conclusions at all can be drawn from the tests with regards to handgun ammunition effectiveness.

My first concern is with the types of projectiles used. We have in the tests two primary types of projectiles: Full metal jacket projectiles, that is lead clad with a thick layer of (usually) copper alloy, and cast lead projectiles, which are just a lead bullet, with no cladding. The jacketed projectiles included the 7.65mm Luger, .38 ACP, and 9mm Luger. The cast lead projectiles included the .476 Eley, .38 Long Colt, .45 Long Colt, and .455 Webley (called the .455 Man Stopper in the tests). The only unjacketed lead projectile representing the small caliber cartridges is the extremely impotent .38 Long Colt, which produces less than two-thirds the energy of 9mm Luger, and even less than the modern .38 Special. So do the unjacketed lead projectiles give their respective cartridges an edge? No one knows, because the Thompson-LaGarde tests didn't bother to control for it. What you can say is that the .45 Long Colt, .476 Eley, and .455 Webley were only fairly compared in this regard with the .38 Long Colt, which is much less powerful than any of those cartridges.

The rotten core of the tests goes beyond that, however. The tests used bovines as their targets, which are not representative of a human being. In fact, a cartridge that may be a wonderful man-stopper may be a terrible cow-stopper, and vice-versa, because the primary disruption of tissue may occur much earlier than is required to quickly dispatch a cow, but at just the right time to eliminate a human threat. A human torso typically does not exceed a foot and a half even at its broadest measurement from armpit to armpit, but a normal cow's width at the heart is around 20"+. Thus, the optimum distance for a bullet to disrupt to incapacitate a man is essentially as early as possible, while for bovines a bullet that expands very early may not reach the vital organs. In addition, the testers were most concerned with how long it took the animals to die, not whether the animal was dropped immediately, or continued to be lively until the time of death.

To further invalidate any conclusions the testers may have drawn, the shooting procedure was completely uncontrolled. Instead of shooting the cattle in a controlled fashion, keeping the number of rounds and locations hit constant between rounds, the testers simply shot at the animals at their leisure, recording the results regardless of whether the weapon jammed or worked perfectly, or whether they hit what they were aiming for or not. The testers also seem to disregard several of their results which ran contrary to the "bigger calibers are better" conclusions, such as the stag which was shot twice with a .476 Eley and was alive and on its feet for four minutes afterward, only to die after five minutes, or the stag that was shot once with a 7.65 Parabellum, and died within 30 seconds, or the bull that took twelve .455 shots to put down. To make matters worse, only 13 animals total were killed, with all calibers, which gives us a sample size of worse than 2 animals per caliber (some were fired at three animals, some at two, some at only one).

As if to add insult to injury, Thompson and LaGarde performed one final test: They hung the cadavers of the animals they killed previously from the rafters of a barn, and measured the sway of a cadaver as they shot at it. No standard was used against which all rounds were tested, and no measurements were taken, the testers simply looked at the sway of the cadaver and assigned it an arbitrary number value.

In short, the tests were a mess, and no conclusions whatsoever can be drawn from their data. The article asserts that Thompson and LaGarde's famous conclusion (which, by the way, includes an addendum that all but admits that all pistol rounds are terrible stoppers, and that the best way to stop a foe is to pour lots of fire into him quickly) was the product of soldierly duty, rather than conviction, that they felt the need to come up with some answer, rather than return empty handed. I cannot speak to this. However, the fact that the tests have been used for over a century as evidence of the great stopping power of large-caliber rounds is a travesty to anyone with a scientifically inclined mind.

The fact that the tests were a complete bust does not prove that the .45 ACP sucks, but a fairly cursory examination of the cartridge alongside its stablemates does pale it in comparison.

First, let's address something that is often repeated on the Internet and at gun shows and in gun stores nationwide: "The .45 ACP is a much better stopper than 9mm, because it is much more powerful."

But is it, really?

Well, first, "power" is a scientific term referring to the rate at which energy is transferred, but what the gun show John Brownings are really referring to is energy. Which cartridge has more energy, 9mm, or .45?

Well, they're about even, actually.

A standard 9mm load produces about 1,200 ft/s with a 115gr bullet from a 5" barrel. This is pretty common performance for training or FMJ loads at standard pressure. Since the English system is all whacked, we're going to convert these figures to metric before we do the energy calculation (trust me, it's easier this way):

1,200 ft/s / 3.28 ft/m = 367 m/s

115 gr / 15.43 gr/gm = 7.45 gm

Naturally, the equation for energy is one half mass times velocity squared:

.5 x 7.45 gm x (367 m/s)^2 = 499 J

A standard .45 ACP ball load, for comparison, produces around 850 ft/s with a 230 gr bullet from a 5" barrel:

850 ft/s / 3.28 ft/m = 259 m/s

230 gr / 15.43 gr/gm = 14.91 gm

.5 x 14.91 gm x (259 m/s)^2 = 501 J

Source: Hodgdon, using WSF powder.

That's right, standard pressure 9mm ball loads are pretty much directly comparable in energy with standard-pressure .45 ACP loads. Now, sometimes you'll see cheaper plinking loads that produce less velocity, and often 9mm is shot from 4" barrels, where .45 is normally shot from 5" barrels, but in an apples-to-apples comparison, they're about the same.

But why? The .45 is much larger, surely it should be more powerful. Yes, but the .45 ACP is much lower pressure (circa 22,000 PSI) versus the 9mm (circa 32,000 PSI), which accounts for its pretty mediocre performance.

OK, fine, but what about lighter weight .45 loads? That's what most people use for self-defense, the 185 gr JHP +P of whatever name brand, right? OK, sure, but to make sure it's a fair comparison, we'll compare it to the 9mm +P. I'm taking my data from BallisticsByTheInch so that there can be no question of the sources.

9mm Luger 115gr JHP +P from Corbon, 5" barrel:

1,372 ft/s or 418 m/s

115 gr or 7.45 gm

.5 x 7.45 x (418^2) = 652 J

.45 ACP 185gr JHP +P from Corbon, 5" barrel:

1,149 ft/s or 350 m/s

185 gr or 11.99 gm

.5 x 11.99 x (350^2) = 736 J

Ahah! The .45 ACP pulls ahead with 13% more energy! Well, yes, of course it does, because it is using a shorter bullet than the standard load, allowing it more case capacity. The 9mm, on the other hand, is using the same weight, and presumably length bullet (if anything, it's longer, because of the hollow point) as the standard load.. BallisticsByTheInch does not provide us with an analogous short-bullet load for 9mm (the 90gr Corbon is using a .380 ACP bullet, seated to the same depth as a 115gr bullet), but such things do exist. Regardless, the 9mm isn't that far behind the .45, even at these cranked-up pressures. However, if that 13% greater output sounds good enough for you, you might want to consider...

The .45 ACP is really, really heavy.

The weight of individual cartridges might not seem like a big deal for a handgun with only a handful of cartridges in the magazine, but consider that the effective handgun is the one you carry around with you all day. A 9mm cartridge with a 115gr bullet weighs about 12 grams, while a .45 ACP cartridge with a 230gr bullet weighs about 21 grams. With a 185gr bullet, the .45 weighs around 18 grams. Even with the lighter ammunition, .45 still weighs 50% more than 9mm, meaning that you have the choice of either carrying fewer rounds, or being saddled with the extra weight. In addition, the .45 ACP is much bulkier, taking up about 60% more volume than 9mm. Is 50% greater weight and 60% greater volume really worth 13% more muzzle energy, and heavier recoiling cartridge? Well, that brings me to...

The .45 ACP has plenty of extra recoil.

Recoil is perhaps the most important aspect of a handgun cartridge in informing how easy it is to shoot. The heavier the recoil of a cartridge, the more time needed to recuperate from a shot, the harder it is to get back on target, and the more you will have to train to become proficient with it. A 9mm standard-pressure cartridge firing a 115gr bullet on 5.7 grains of WSF at 1200 feet/second produces 3.2 kg-m/s recoil impulse and 7.5 J recoil energy, while a .45 standard-pressure cartridge firing a 230gr bullet on 6.4 grains of WSF at 850 feet/second produces 4.4 kg-m/s recoil impulse and 14.0 J recoil energy, or 38% more recoil impulse and 87% more recoil energy! You might say you are willing to handle the extra weight and recoil so you can take advantage of the .45 ACP's additional energy, but that leads me to my next point...

All pistol rounds pretty much suck, regardless of their caliber.

Pistol rounds are right at the edge of what is needed to stop a human being reliably. Few pistol rounds produce over 800J, and most intended for self-defense produce around 200-500J energy. A pistol round may be enough to stop someone by virtue of that person probably not having been shot before, and thus being taken by surprise, but against an undeterred enemy, many, many pistol rounds will most likely be required to stop him. Pistol rounds, whether they be 9mm, .45, .40, or .380 ACP, produce similar wound channels if they have similar bullet construction. FMJ bullets will perform the same typically, more or less regardless of what tissue they hit. They produce a tubular temporary cavity, and a relatively mediocre permanent cavity. Third-generation jacketed hollowpoint bullets, like the Gold Dot or Hydra-Shok are better, but they don't perform the same against bone as they do against soft tissue. But don't despair just yet, for there is hope...

Fourth-generation hollowpoint bullets are pretty good, actually.

Fourth-generation all-copper based bullets, like the Barnes TSX/DPX/TAC-X and the Hornady GMX perform rather well versus bone, and expand to impressive diameters (see the above tests versus bone simulant) in the .7-.8" range. They also tend to hold together better versus harder targets, like wood, steel, aluminum, and glass, instead of falling apart like third-generation bullets. Monolithic copper-based bullets don't have the problem of core-jacket separation, and afford light bullet weights, high velocities, lighter recoil, and good short-barrel performance. Because they are ductile enough to deform, but hold together reliably, they dispense what energy that pistol cartridges do have effectively and consistently throughout their travel in the body. Because of this, they offer an excellent alternative to conventional jacketed hollowpoint bullets in any caliber.

So the .45 ACP performs about as well, or perhaps marginally better than the 9mm against human targets, but at the expense of much greater bulk, weight, recoil, and cost. Is it worth it? No. If you need more punch than 9mm, get a .40.