Stopping power of various handgun rounds

Is there a universally accepted measure of stopping power?

Rounds that penetrate deeper, like the 9mm, are (I’ve always been taught) less effective than .40 S&W or .45 ACP.

But is there an index that balances out size, weight, projectile penetration, and other relevant factors and has a definitive answer, or is the field too complicated for such an analysis?

(I ask because (a) I’ve always been curious, and (b) I’ve been looking at the .50 Mag S&W, which I’d consider a bit of overkill in the stopping power discussion, unless we wish to discuss stopping the 6-car Orange Line train to Vienna.)

There is no universally accepted measurement for “stopping power.” That is what makes all the arguments so vehement. Each side has valid points. Some go for FPS and penetration. Others go for “flying ashtrays.” The .40S&W was an attempt to get both. You pay your money and make a choice. Personally, I own all of them. But for concealed-carry, my choice would be something in .45ACP. Just my preference, mind you. By the bed is a 9mm. :smiley:

Hijack/piggyback. Can you use E=MC2 for this application to determine the amount of energy delivered to a target?

The rest of the OP I’m guessing will need to consider bullet hardness, to determine how quickly and how much a bullet will expand on impact vs. pass through the target; as well as the amount of energy invested in the bullet.

Personally I like the .22 for multiple stings and all but zero recoil & easy target reacquisition. :smiley:

I have owned all of them, at one time or another, as well as a little .25 auto that would have been of great utility if I ever got into a shootout inside a small elevator.

But while I’ve shot many a paper target, I have no idea how any of my rounds would actually do in terms of stopping a person. I realize there are so many variables involved - location of shot, mass of target, presence of drugs or alcohol, etc… but it surprises me that there isn’t a universally-accepted way to measure this.

Too many variables to be useful. Evan Marshall has done a statistical analysis of “one-shot stops” that is interesting. Note that the .357, .40S&W, .45ACP and 9mm all come in at 90% or better.

That would be a “No.” Not unless the rounds were really small nuclear weapons! :smiley:

The formula you want is F=ma.

“Stopping power” with regard to firearms is a meaningless term. There are a number of factors that determine how incapacitating a round is–most significantly, how deeply it penetrates and how well it expands–but these measures are complex, depending on the speed of the round, weight of the bullet, configuration of the jacket, what kind of material it has to penetrate through (leather, fur, and wallboard will tend to plug up any hollowpoint round, making it act like a FMJ), and cannot be simplified to a simple calculation of energy. FWIW, it appears that momentum is actually a better measure of “stopping potential”, but again, that’s only a general guideline. While I can’t find a direct link to the study, the FBI did an assessment based upon forensic data which demonstrated that the 125 grain .357 Magnum JHP out of a 4" barrel gave a 92% “one shot stop” rate for center of mass hits. IIRC, the 230 grain .45 ACP JHP gave something like 85%, and it went downhill from there. This is field data, though, and is therefore limited and uncontrolled in terms of environment and reporting. Here (warning: PDF) is a dissertation on ballistic wound similuation, which will tell you more than you ever wanted to know about ballistic trauma simulation.

The 10mm Auto was an attempt to replicate the same penetration and energy of the .357 Magnum in an autoloader. (The .400" round was selected, in part, because it offered greater powder capacity…and no doubt because Col. Jeff Cooper, who was part of the development effort, is a .45 ACP afficinado and wanted nothing to do with popgun rounds like the 9mm.) The .40 S&W was an attempt to package the low end ballistics of that round into a more comfortable size.

Essentially, once you’re past the issue of sufficient penetration (which rounds like the .22LR and .25ACP do not assure) shot placement is the largest factor determining how effective an individual shot will be. One carefully placed 9mmP is worth a magazine’s worth of .40S&W that all miss the target. General rule of thumb is to get the heaviest round you can comfortably and accurately shoot, be it a .38 Spl. or a .45 ACP. (A .44 Mag or .50 AE is probably taking that to an irrational extreme, though, with respect to a human target.)

But here’s to hoping you never have to find out about this firsthand, eh?


Unless you happen to know of a place offering a concealed carry mass-driver, in which case you should post it :slight_smile:

My daddy always prefered the .357 Magnum, so that’s what I learned with. I love it.

I get weird looks from the “kids” at the range, though, firing a big clunky revolver! I am only 5’1" and look younger than 37.

My brother has quite a stash, has a 9mm as his primary personal weapon but was using a Glock for work and liked it.

There are two distinct schools of thought on handgun stopping power.

The first, as espoused by Marshall, Sanow and Ayoob(all cops/former cops and gun writers), advocates lighter, higher velocity rounds, under the concept that the impact energy is the important factor in stopping power. This school uses “one shot stop” statistical data gathered from actual police shootings to demonstrate their points. Something like a 125 grain 357 Magnum at is their ideal round.

The second school of thought, as espoused by Dr. Martin Fackler(sometime Chief of US Army Wound Ballistics Laboratory), recommends heavier and larger bullets in order to obtain greater momentum and wounding capacity. In other words, to put a bigger hole in someone. Fackler and his adherents tend to use a more theoretical approach with ballistic gelatin and scientific testing. Fackler’s ideal is something like a 230 grain 45 ACP at 950 fps.

I tend to agree with the Fackler school of thought, if only because I put more trust in experimentation and replication than with statistical analysis of real world events. Marshall and Sanow can’t really control for very much, for example range, shot placement, bullet path, drug use by perps, etc… so I look at their data a little cockeyed.

Actually, you either want KE=1/2mv[sup]2[/sup] (how much damage the bullet will do) or momentum=mv (how far its going to knock you on your ass).

Bricker, silenus & Inigo -I knew I liked you guys for a reason! :smiley:
I too have a Glock 9mm for carry with alternateing HP and FMJ, a .357 for home with those Rhino type hollow points with the little pellets inside and a 12ga. five shot pump I like to call “the Crowd Pleaser”. A Deputy I knew called his “the alley sweeper”. I love the elevator shoot-out mention.
IIRC, the .40 was developed and used for awhile by the FBI looking for good knock down power and one-shot-stop capability but with little penetration. The idea being, if it goes straight thru the perp and on down the crowded city street it may not turn out well.
As to caliber size I can say this. I have buried two friends from hits with a .22 LR (seperate incidents), another who survived (with some paralysis) 5 hits by a .32 auto, another survived a shotgun blast losing the outer portion of the left thigh and another who took a .38 through the shoulder saying it felt like being hit by a night-stick, and he would undoubtably know. Another friend only uses a Ruger Red Hawk .44 mag (I guess in case he needs to drop a charging Cadillac or something) and scoffs at mine.
As others have stated, it probably depends on what you a comfortable in handling and where the shot is placed.

Treis is correct, you want kinetic energy, not momentum. Perfect example is those of us that played football or rugby. It’s not the big guy that puts the big hit on you, it’s that little bugger that’s super quick. Velocity squared

Also keep in mind that the bullet has to STOP inside you for maximum effect (either by using soft metals - i.e. ‘mushrooming’ or perhaps by using the new frangible type bullets.)

But if you watch “mythbusters” on discovery channel, they did a show where they tried to replicate the “blowback” that a gunshot victim supposedly has. (Where you get blown off your feet backward when shot in the chest). They determined that this just doesn’t happen with handgun rounds…

now a 12 guage on the other hand…


Personally, if you want crazy overkill…choose a S&W .500 Magnum.

(Personally, I like point number three)

Most Powerful Production Revolver in the World Today

Massive 500 S&W Magnum® Cartridge - 2600 ft/lb. Muzzle Energy

A Hunting Handgun For Any Game Animal Walking

It’s got the impact of a .308 round, and the bullets cost about 4 bucks a piece. Definately not for “plinking”…

But the next time you’re faced with a charging '57 Chevy…


An additional factor in real world data is the theory that many “stops” are mental. I hate popping into a GQ thread without a cite handy, but I saw a study a few years ago on stopping power that indicated that a large cause of people “going down” when hit by a bullet was simply that they were conditioned to “know” that if you are hit by a bullet, you will fall down. Essentially, if your leg is not blown off and you are not hit in the heart or spine, most adults can stay standing after a bullet hit of almost any type until they bleed out.

Sigh. Now someone will want a cite. I better start searching.

This is the phrase that stops me cold in the thread. You’re a lawyer, so you know about advice. I’m active duty military (who happens to be a darn avid shooter), so I hope you take mine into consideration: find a caliber and gun that fits you.

Stopping power is great and all, but if you can’t put a round on target because the gun is so big in your hands that it’s unwieldy, it’s useless.

When I go camping, I take my .357 Ruger SP100 (apparently, a Security Six clone!). It’s mechanical reliability and it’s fit in my hand are perfect for aggressive wildlife. Or, I take my Charles Daly .40SW DDA, because it fits so good . . . again in my hand.

If you can, go to a few ranges who rent you guns, and try 'em out. Caliber is secondary next to accuracy.

. . . and yes, I’ve been caught by javelina in AZ, and sent a few rounds into the dirt to scare 'em off.

I was at a gun dealers last Saturday and asked him just that (the OP). He pretty much agrees, it depends. He showed me this as an example of perhaps a good choice. For being so tiny, and it is tiny, it felt very comfortable in my hand.
Anyway, what’s the difference between .357 magnum and .38 special?
BTW; I won’t be buying one. Not where I live.

A fairly good “POW” or a Ka-Fuckin-BOOM!!
Seriously, the amount of powder as demonstrated by the lenght of the shell casing.

So that gun would fire either round. Cool. :cool:
Guess which one I’d load. I like shiny things, and loud noises.

The .38 was the original pistol. A few years later, they developed the .38 SP (Special) to increase the velocity of the round, increasing it’s power.

The .357 Magnum evolved out of the .38, starting with the ‘name’ of the caliber. Most .357s will shoot a .38, but not a lot of .38s will shoot a .357. The caliber may be confusing, but a lot has to do with the chamber pressure on firing. So, if you want to shoot both, try a .357, but not a .38 (which may not allow the powder pressures of a .357).

I own both. It’s weird, but a matter of advertising back in the '30s.