LJ Bonham is a semi-subsistence hunter, hunting magazine editor, and firearms enthusiast who lives in the Rocky Mountains.
Once all the hype and myth are discarded, self-defense handgun cartridges are all the same. A bold statement. The notion a 9 mm is as good as a .45 is as good as a .38 is as good as a 10 mm, ad infinitum, is enough to cause many people to become unhinged. In fact, it looks like a fanboy mob has just gathered on my front lawn. They’d just waste their energy. A good many other folks who are knowledgeable about such things, including the FBI, would agree with the article's premise. The margin between common self-defense cartridges' terminal performance is slim, if it exists at all.
This article draws heavily from several sources. One is Mr. Evan Marshall who co-authored a book in the 1980s with gun expert Edward Sanow, entitled Handgun Stopping Power: The Definitive Study. Marshall worked as a Detroit homicide detective. He has seen the end result of all too many gunshot wounds. Marshall and Sanow set out to determine how effective handguns stop an assailant from assaulting their intended victim.
They pored through countless police shooting reports, newspaper accounts, and autopsies to determine, by caliber and load, which cartridges produced a one-shot stop more than others. I won’t recapitulate their research here, readers should read the book for themselves. Mr. Marshall has updated his statistical tracking as new shooting data became available.
Marshall and Sanow’s work is by no means comprehensive. Nor does it have true scientific validity as it is not a controlled, peer-reviewed study. Its primary value here is to document how each caliber performs relative to the others.
The other major source is, oddly enough, a YouTube channel: Tnoutdoors9. The gentleman who produces content for this channel is different from most found in the internet video wasteland. He uses sound, repeatable methods to test self-defense cartridges. He fires off-the-shelf, commercial ammunition into calibrated test media and performs a detailed analysis of the results. While gelatin tests are not the final word on how a bullet will perform when it hits live flesh, it does provide a controlled, repeatable baseline to compare cartridges one to the other. I have neither a personal nor a business relationship with this channel's producer. I happened upon his videos through a generic YouTube search.
Additional sources are: "FBI Executive Summary," dated 6 May 2014, regarding Bureau adoption of the 9 mm, reprinted on the website LooseRounds; Handgun Wounding Factors and Effectiveness ( SA U.Patrick, FBI Firearms Training Unit, 1989); and 9mm vs .40 Caliber (Sydney Vail, MD, Police Magazine, 22 January 2016).
The final source, while anecdotal, is actual gunfight analysis. In particular, two significant law enforcement shootouts: the 1986 FBI incident in Miami, Florida, and one in 2017 which involved the Pennsylvania State Police.
Handgun Terminal Ballistics (Warning: May Contain Science)
Before one can compare terminal performance between cartridges, it is necessary to understand how bullets incapacitate humans.
Most bullets travel at supersonic velocity which gives them tremendous energy, expressed as foot-pounds (ft-lbs.). Handgun bullets fired from common defensive cartridges generate between 200 and 700 ft-lbs. By contrast, military rifle cartridges produce anywhere from 1200 to 3000 ft-lbs. Handguns are not powerful compared to rifles. Someone who knows they are going into battle takes a rifle, not a handgun. Handguns are, at their core, backup or emergency weapons.
The Two Cavities (More Science)
Bullets create a temporary stretch cavity and a permanent stretch/crush cavity in live tissue.
Flesh is ninety percent, or so, water. Fluids are not compressible. The bullet’s energy transfer creates a balloon-shaped shock wave (temporary stretch cavity) inside tissue. This shock wave shakes and, if it’s strong enough, tears tissue. If the bullet is designed to expand, this energy transfer occurs at a very high speed in an instant and then dissipates. If the bullet does not expand, it still creates a shock wave, just not as severe.
A permanent stretch cavity is left in the tissue after the temporary one collapses. It is shaped like the temporary cavity, just smaller. Any tissue the bullet itself hit on its way through the body is included in the permanent cavity.
A bullet wound’s severity varies in direct proportion to the energy it possesses at impact, how much energy it transfers to the target through the temporary stretch cavity, the permanent stretch cavity’s size, and what organs it strikes (Patrick, Vail).
In short, a bullet must hit the right thing, in the right way, to have a significant and timely effect (Vail).
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The Real One-Shot Stop
Bullets, even those fired from a rifle, have a limited chance they will drop an assailant right then and there. They must damage the brain or spinal cord. A heart or lung shot may not incapacitate for several seconds or even many minutes. Someone can do much harm during this time (Patrick, Vail).
Bullets that impact at over 2600 feet per second can induce hydrostatic shock. The body’s entire neural network is overwhelmed by the bullet’s shock wave if a bullet passes too close to the spinal cord or a major nerve plexus. The central nervous system shuts down for several seconds or minutes. If the bullet also hits a major organ and causes massive blood loss, the target can die. If not, the target can wake up and resume activity. This explains accounts from hunters about animals they saw go down and then get up to run off. While some experts are skeptical about this theory, even the proponents acknowledge handgun rounds cannot induce this effect due to insufficient velocity and energy.
Handguns are imperfect self-defense tools compared to rifles. One should not rely on them to stop an assailant in an instant.
Busting The “Best Handgun Cartridge” Myth
Defensive handgun calibers cause similar wounds to each other because they generate energy in the same limited range (FBI), as this muzzle energy list, based on bullet weight and factory velocity, demonstrates.
- .380 ACP, 95 grain: 190 ft-lbs.
- .38 special, 158 grain: 200 ft-lbs.
- .38 Special +P, 125 grain: 248 ft-lbs.
- 9 x 19 mm, 124 grain: 345 ft-lbs.
- 9 x 19 mm +P, 124 grain: 410 ft-lbs.
- .40 S&W, 165 grain: 476 ft-lbs.
- .44 Special, 200 grain: 360 ft-lbs.
- .45 ACP, 230 grain: 369 ft-lbs.
- .45 ACP +P, 185 grain: 534 ft-lbs.
- 10 mm Auto, 200 grain: 537 ft-lbs.
- .357 Magnum, 125 grain: 583 ft-lbs.
- .41 Magnum, 210 grain: 705 ft-lbs.
- .44 Magnum (reduced load), 210 grain: 729 ft-lbs.
The most common rounds used by law enforcement these days (9 mm, .40 S&W, and .45 ACP) range between 345 and 534 ft-lbs. If the .45 +P is thrown out, the difference is less than 150 ft-lbs., which is not substantial. Further, the 9 mm +P and standard pressure .45 ACP have almost identical muzzle energy. To get much beyond this range requires magnum revolver cartridges that have substantial recoil and limited ammunition capacity.
Semi-Auto Cartridge Gel Tests (9 mm, .357 Sig, .40 S&W, 10 mm, .45 ACP)
Tnoutdoors9's results show .40 S&W and .45 ACP average 14 inches penetration. These bullets start with a larger diameter and retain this advantage when they expand. The .45s mushroomed to around 0.75 inches and left 1.0 – 1.5 inch wide permanent stretch cavities, but with lengths similar to 9 mm. The much less common .357 Sig produces similar results. The .380’s cavities are narrower and shorter, with around 10 inches of penetration. The powerhouse 10 mm Auto didn’t live up to its hype. Permanent stretch cavities are on a par with .45 ACP, but it does penetrate a bit more. Remember, too much penetration is as problematic as insufficient penetration when it comes to self-defense cartridges.
Tnoutdoors9 has published numerous gel test videos and it is beyond this article's scope to include them all. Readers are free to view the full selection on their own and note how similar each cartridge performs compared to the others.
Semi-Auto Street Results
Here is Evan Marshall’s most recent one-shot stop online data for semi-auto cartridges. These stats are not the final word, and even Mr. Marshall advises approaching them with caution. Full results are available on Hendon Media’s website.
- .380 ACP: 68 – 70%
- 9 mm: 88 – 91%
- .357 Sig: 89 – 94%
- .40 S&W: 90 – 94%
- .45 ACP: 88 – 96%
The above numbers are for expanding bullets. All the calibers perform almost the same. High-velocity and larger bore calibers have a slight, statistically insignificant, edge for a few, specific loads, but the 9mm is more consistent across all loads. Since Marshal's data relies on small data sets, it has limited predictive value for one-shot stops, but it does illustrate the overall similarity between calibers.
Here’s what FMJ looks like.
- .380 ACP: 55%
- 9 mm: 70%
- .40 S&W: 71%
- .45 ACP: 62%
All within close proximity to each other. Based on this data, the .45’s theoretical advantage with non-expanding ammo doesn’t hold up in the real world as often as some would believe.
Revolver Cartridge Gel Tests (.38 Special, .357 Magnum, .41 Magnum, .44 Magnum)
Tnoutdoors9 tested several .38 Special +P loads. On average, they create permanent stretch cavities between 0.357 and 0.75 inches wide, 2.5 to 3 inches long, with 12 to 14 inches total penetration. He had some failures to expand due to the lower velocities produced by the 2-inch barrel on the test revolver. Even when shot from the snubby, the .38 +P transfers less energy to the target, but penetrates the same as the other calibers discussed so far.
Magnum revolver cartridges should do better, based on reputation. However, the .357 Magnum’s permanent stretch cavities average 1 inch wide by 5 inches long, and penetrate 14 to 15 inches. All are quite similar to 9 mm, .357 Sig, .40 S&W, 10 mm, and .45 ACP.
Tnoutdoors9 has not, as this is written, tested the .41 or .44 Magnum. Based on the best tests I could find on the internet (there are few proper ones out there), the .44 Magnum in its full-house guise has excessive penetration for self-defense use against human assailants. Loaded with lighter bullets at lower velocity, it performs on par with the .357. Full power .41 Magnum loads come close to the reduced .44’s energy, so should perform the same.
Revolver Street Results
There is limited street data for the big-bore magnums. They are not popular with either law enforcement or armed civilians. Marshall’s original book, with small data sets, predicted they would produce one-shot stops in the 80 – 90% range. The .357, on the other hand, has many data points. Marshall’s 2004 update shows this cartridge is an excellent round with 86 – 91% one-shot stops for the best loads. Same as the 9 mm.
Anecdotal evidence is fraught with pitfalls, but historical gunfights provide some lessons vis-à-vis handgun cartridge similarity.
FBI research, as well as accounts from such legendary gunfighters as William Fairbairn and Jim Cirillo, indicate even trained personnel hit their target two or three times for every ten rounds fired in a shootout. This suggests high magazine capacity is vital (Vail, FBI). Once the shooting starts, people fire as many times as they can as fast as they can, and people involved move in every conceivable direction. There is often little, if any, time to reload, so you’re stuck with however many rounds are in your gun at the moment.
Modern law enforcement firearms training recognizes this fact. Most agencies teach officers to shoot until a target is neutralized; not to rely on just one or two rounds.
FBI vs. Bank Robbers, Miami, 1986
This shootout has become legendary. People often draw conclusions from it based on their own biases. Still, the tragedy sheds light on actual defensive handgun effectiveness.
One suspect had a high-capacity rifle while the FBI had 9 mm's, .357's, and shotguns. Platt's suppressive fire prevented many agents from returning effective fire and overwhelmed those caught in the open. Fire superiority is a bedrock tactical principle.
Most pistol cartridges would not have fared better at the time with a cross-torso shot on a man as large as Platt. Since then, handgun ammunition has made great leaps forward, but it is no substitute for sustained fire from rifles.
Pennsylvania State Police vs. DUI Suspect, 2017
Fast forward thirty-one years. Two Pennsylvania State Troopers attempted to arrest a DUI suspect. The suspect grabbed a gun and a protracted firefight ensued. I won’t post the dash-cam video; readers can find it on the internet. Suffice to say it is terrifying to watch.
One trooper became pinned down between the suspect’s car and a highway guardrail. Both he and the suspect emptied their guns at each other from less than fifteen feet. The suspect had partial cover from the car’s roof and rear window.
The second trooper engaged the suspect who stopped shooting and jumped into his car. The trooper’s fire shattered the car’s back window. Then, the suspect drove off at high speed and arrived conscious at a local hospital minutes later. Police took him into custody without further incident.
The troopers were issued semi-auto pistols chambered in .45 ACP. They hit the suspect three times: hand, torso, and neck. One bullet lodged in the suspect’s skull. The wounds had no significant effect on the suspect.
One trooper sustained a wound in the neck and one in the leg which severed his femoral artery. He continued to fire at the suspect.
The troopers fired over twenty rounds, the suspect many as well. Just five bullets hit anyone involved. Neither suspect, nor troopers, received a hit to the central nervous system, and all remained in the fight for its duration. The vaunted .45 ACP proved no better, or worse, than the much-maligned 9 mm in Miami. In fact, its heavier recoil may have degraded the troopers’ aim more than a softer recoiling round.
Current research indicates there is no distinct advantage based on a particular handgun cartridge. If, in fact, all handgun rounds provide the same effectiveness. The deciding factors are magazine capacity and lower recoil which allows a shooter to put more rounds on target in a shorter time period. More hits mean a greater chance one or more bullets will find vital organs (Vail, Patrick, FBI). Hits are more effective than misses, regardless of the cartridge's power. One must assume assailants will pose a threat even if shot multiple times. Maneuver and cover are just as important to gunfight survival as the gun. All self-defense handguns have limited power compared to rifles, and provide similar terminal performance across calibers.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2018 LJ Bonham
Nick Miller on August 14, 2020:
The deciding factor for me is that the 9mm has been seen to hit bone and ricochet into other areas of the body non-lethally. There are endless examples in gang documentaries of people shot with lighter rounds where the round ricochets off bone. In one example, an individual was shot in the face and the 9mm round ricocheted off their cheek bone, went through their tissue down their collar bone, beside their torso, and into their thigh, ultimately doing non-lethal damage. On the advice of paramedics and soldiers, I prefer 180 grain 40 S&W, and more particularly 230 graiin 45 ACP, because it crushes bone and breaks through it instead of ricocheting. There are many examples of individuals being shot in the head, and there being enough skull-resistance that the round stops in their brain, ultimately leaving them alive even if they are incapacitated. You want the heavier round to make sure that your shot placement pays off. Against more physically capable enemies who dodge quickly in a shootout, capacity is still king to make up for misses and resultant poorer shot placement. This is my opinion, and I note that articles like this one are like a political advert for 9mm. Gel tests do not simulate either tissue or bone well. Perhaps see Paul Harrell's meat target testing for a much more authoritative example of effectiveness. Ricocheting bullets are a minor factor, it may seem, but in shooting scenarios, it is incredible how many times outlier examples seem like the rule, because bullet ricocheting is very, very prevalent. Can't go wrong with 9mm, though, of course.
KM on July 05, 2020:
Ama I missing it? I do not see .22 listed in any of the research cited by this article.
Hans Gruber on September 20, 2018:
And this supports my own belief in the 5.7x28 as and ideal CQB choice? The Ft. Hood shooting also supports that thinking.
Two to five rapid hits from a 5.7 are every bit as good as the bigger bores, and I believe better due to the non-linear wounding common to small, lightweight bullets passing through tissue.
Kilibreaux on September 20, 2018:
This article supports the reality that using a lowly .22 for SD is viable. Based on real world evidence the .22LR has equal chance to reach a vital structure, and failing to do so, has equal probability of limited apparent effect.