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Before I started down the road of responsible gun ownership, my perceptions about guns were shaped by Hollywood. Like most people that accept what they see on TV or sliver screen as gospel, I thought that guns were guns. You chose one based on the “cool factor” (.50 cal Desert Eagle), a desire to emulate a Tinseltown hero (.44 Magnum/Dirty Harry) or a desire to “go retro” (a wheelgun for Film Noir fans, or a six-shooter for Western buffs). None of this, of course, was useful, practical intel. When it comes to personal defense, you’ve got to choose a weapon that can get the job done. In the pistol packer’s parlance, that’s called “stopping power.” And it’s serious business.

If you shoot somebody, are they gonna be able to keep coming at you or will one shot put them down for the count? In a gunfight, it’s not enough to shoot someone. You have to stop them from hurting you, regardless of what happens later. It’s actually possible to shoot the bad guy and have him die from his wounds—just after he’s killed you. Not good. Nope, you want to fire rounds that stop them first, kill them (maybe) later. Killing the bad guy is a secondary goal to stopping them and eliminating the threat to you and yours.

So what makes one gun/bullet better at dropping the bad guy(s)? There are a large number and wide variety of factors involved. Physics. Anatomy. Biology. Psychology. Pharmacology. Ballistics. And more. When discussing the effect of a bullet on a human being, there’s a LOT of science out there, somewhere. Most of it centers on terms called expansion, penetration, temporary cavitation, and a little something the guys in the white coats like to call hydrostatic shock.

You don’t have to be Mr. Wizard to fire a gun to wound or kill your target. Plenty of people simply notice the fact that paper targets give you more points for some shots than others, aimed for those places and called it good. It may be just as well; there’s a large dichotomy between laboratory tests and real world results. But the basics are worth noting.

Stopping power can be defined by three basic parameters: the bullet’s size, speed (the amount of energy behind the bullet when it leaves the barrel) and on-target behavior (what it does when it strikes a target).

As we’ve learned, a .22 caliber bullet is smaller than a .45. In fact, it’s less than half the size of a .45 round. All things being equal, you’d think the .45’s mass would give it more stopping power than a .22. And you’d be right. Generally speaking, the bigger the bullet, the greater the mass. The greater mass, the greater the stopping power.

The force behind the bullet is determined by how big the cartridge is, and how much gunpowder it contains. Again, all things being equal, the larger the gunpowder-to-bullet mass ratio, the greater the bullet’s stopping power.

So why not just get a big ass gun? The main limitation: recoil.

A .50 Desert Eagle and a .357 Magnum offer devastating firepower, but they kick like a mule on steroids. If a novice shooter misses his target with the first shot (a distinct possibility), he’ll have a hell of a time placing the second shot where it needs to go. The owner of a “lowly” (and low recoil) .22 may have less energy at his command, but he may also be more accurate, more quickly, more often. All of which could make his small gun more effective than he would be firing a big ass gun.

The secondary limitation: gun size.

It’s often said that the best gun is the one you have. You could have a Howitzer in your closet, but a .22 in your pocket would be a lot more effective for personal defense. When choosing a gun – bullet combo, you have to balance size with practicality with stopping power.

But the most important factor is accuracy. It’s not the number of rounds or the size of the bullets that counts the most. It’s where they go.

The way a bullet expands and deforms when it hits something solid (e.g., the flesh and blood human being) will determine how much damage it will do to your target. As we discussed in a previous post on ammo, hollow-point bullets will do one Helluva lot more damage than a FMJ roundball cartridge; the hollow-point is designed to expand into a jagged flower-looking thing that eats soft tissue for lunch.

Unfortunately, “designed to” does not always equate to “does.” There are a lot of hollow-points bullets that, under real-life conditions, fail to expand. When they strike a target, they behave a lot like their much less expensive roundball relations.Which is to say not as effectively/

Combine all these factors and you can end up with some interesting—and unexpected—results. A number of police officers have told me that, if given a choice, they’d rather be shot with a 9mm or .45 than a .22 round. The .22 tends to enter the body with just enough velocity and energy to hit bones and ricochet around, damaging a whole buncha internal organs. A 9mm or .45 general goes in at a straight line and either stops or exits the body.

Ever wonder why cops don’t all carry .44 Magnums or .50 Desert Eagles? It’s because when you’re in law enforcement, you want a round that’s gonna hit your target, penetrate, and then stop. What you DON’T want is your round to hit your target and keep on going without losing at least some of its energy.

A .44 Magnum is perfectly capable of putting a nice-sized hole through an engine block. Imagine what that kind of power would do if someone shot a bad guy standing in front of you. And the guy behind him. And behind him. Not pretty.

I’ve also learned that a 9mm round doesn’t have as much stopping power as a .45. The .45 ACP is sub-sonic. It travels more slowly than the 9mm; it will do more damage at that comparatively leisurely pace than the faster 9mm round. The advantage of the 9mm: smaller cartridges allow for magazines that hold more rounds. It also has slightly lower amounts of recoil when compared to a .45.

Yes, but, Smith & Wesson sells a .40 round for a .45 weapon that splits the difference between the .45 caliber bullet and the smaller 9mm round. It offers the greater stopping power of the venerable .45 load in a less, uh, dramatic fashion. There are reports of misfires but . . . ain’t capitalism grand?

A majority of professionals shoot 9mm because they have to (department regs.). Many holster a .45 because they can and it works (with a growing number moving to the .40 S&W round). More law enforcement guys favor semi-autos over revolvers because they allow for more rounds and faster reloading. For those that do shoot wheelguns, the .38 Special seems to sit in the sweet spot between firepower and recoil.

Confused? We’ll, lets leave it at this: the best caliber is the the one you have in the gun in your hand when push comes to shove. Stopping power is not an insignificant factor, but if you’re facing a bad guy with a little .22 in your mitt, the answer isn’t “get a better gun.” It’s “stop the bad guy from hurting you.” Or, more precisely, be precise. And that means practice. Practice. Practice.

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  1. I think most of what is said about "stopping power" is bull. No small pistol caliber is going to deliver enough energy to "stop" someone unless it hits them in a vital area and kills them. Plenty of people have been shot by plenty of rounds and kept going. Pistol wounds are survivable.

    In terms of bullet size, a .223 rifle bullet is smaller than a .45. And a 9mm. But there is a lot of powder behind. Speaking in terms of handgun physics, you generally either get a small, fast bullet (9mm) or a slow, heavy bullet (.45).

    In terms of ft/lbs of force applied, 9mm can hit as hard, or harder, than .45 because of its vastly higher velocity.

    The .38Spcl and .357 Magnum have bullet sizes that are about the size of a 9mm. The difference again is how much powder, which generates higher velocity.

    You come to the right conclusion that any gun will do you as opposed to no gun, but I strongly advice against buying into the myth of stopping power and the claimed superiority of .45 against the 9mm. Personally, I favor the 9mm and in reviewing all the statistics I can find, I really don't see any reason to doubt it.

    • E=.5mv^2.

      Talking in terms of pure energy, unless the velocity of the smaller bullet is so much faster (squared faster), mass (aka size, assuming identical density), scales much more proportionately.

      In other words, since the velocities of bullets should be approximately equal (or at least would scale less per differential increase as compared to mass.) This seems to be confirmed. Aproximate Muzzle Energy ~369 lb/ft for 45ACP vs. ~304 lb/ft for 9mm.

  2. with the advancements in 9mm I.E POWERBALL 100gr, I feel more than confident if I were to need to fire it out of my Glock 26, however seeing the damage of a .45 into diff targets, it just simply does more damage, now use a plus “P” round and there is a very noticable difference. All the cops, medical examiners and soldiers ive talked to all say the same thing. Recoil, shot placement, follow up shot yes I agree all = stopping power, Just saying if you only hit em once, the .45 acp would be my choice.

  3. Knockdown power is a Hollywood myth. You don’t need another website to prove this, simply recall newtons laws from physics. Most importantly “for every action there will be an equal and opposite reaction. ” what does this mean for knockdown power? The bullet can not release more force on someone than what you felt in the recoil. The bigger the bullet the bigger the hole and the more you bleed. Being able to keep your gun on target so you can make more holes is far more important than this discussion.

    • That’s an absurd point of view for Newton’s Law. I’ve see half-a-hundred videos on youtube of idiots firing a handgun and it flies right out of their hand(s). You are on the right end of a machine designed to fire an object in one direction, and if your smart, you are braced to fire that shot. If I hit a man with my fist, he is the only one that is going to fall down…

  4. As for stopping power,most of the handgun rounds are not up to the task without firing at least two rounds followed by more rounds if necessary,we never know if the subject you are having to fire on is high on drugs,drunk,already mad from something else,which all of these things can and does lead to a big adrenaline dump,which could lead the subject almost being superhuman,so multiple rounds could be needed to stop the subject.Be prepared and ready.Keep your powder dry.

  5. Outside of a headshot, bullets kill you by making you bleed to death…period. Stopping power isn’t as important as how many holes you can put in them. No pistol caliber has a 100% guarantee to drop a person in one shot. I can shoot someone 2 to 3 times with the controlled recoil of a 9mm in the time it takes to reacquire the target with a 45. Why is everyone so concerned about 1 shot stopping power? There is a reason you have a semi auto with more then 1 bullet. More holes=more blood loss=target incapacitated quicker. Quick double tap with a 9mm is vastly superior to a single shot of a more heavier recoil .45.

    Higher velocity of a 9mm also means more reliable expansion of hollow points. I would take a 9mm over a 45 anyday.

    As far as 22lr you need to depend on accuracy to make it effective. I guarantee in a life and death situation with adrenaline going and no fine motor skills, accuracy will not be on your side. The same “bouncing around” effect a 22lr has inside the body works against it. It will also “bounce” off bones and not allow a good clean hit to vital organs easily. An abdominal shot may kill a person, but not quickly. A 22lr to the chest or skull is a gamble if the bullet will penetrate and hit anything vital. Life or death I don’t want to gamble, I want guaranteed penetration and expansion.

    I doubt you will find one cop who uses a 22lr for a personal self defense gun at home.

  6. There is a reason it is an ongoing debate with no winner… they are both just as deadly.

    Remember: Velocity x mass= total kinetic energy. Everyone forgets the velocity part…

    9mm total kinetic energy =650
    .45 acp total kinetic energy= 425

    9mm actually has more overall kinetic energy.

    .45 is larger but slower and has a better chance of directly hitting something vital.

    9mm is smaller but a lot faster and will cause more surrounding tissue trauma (more energy dumped into the target has to go somewhere) also known as more hydrostatic shock, that has a better chance of damaging something vital, even without a direct hit.

    Both are very deadly. Just in two different ways.

    • Uhm. If you’re going to use physics equations, please at least get them right.
      Velocity x mass= momentum.
      1/2 x mass x velocity squared = Total kinetic energy.

  7. Stopping power in common handgun rounds is total BS.

    “At the core of his desperate firefight was a murderous attacker who simply would not go down, even though he was shot 14 times with .45-cal. ammunition — six of those hits in supposedly fatal locations.”

    “In this free-for-all, the assailant had, in fact, been struck 14 times. Any one of six of these wounds — in the heart, right lung, left lung, liver, diaphragm, and right kidney — could have produced fatal consequences…“in time,” Gramins emphasizes.”

    “When the suspect bent down to peer under the car, Gramins carefully established a sight picture, and squeezed off three controlled bursts in rapid succession.
    Each round slammed into the suspect’s head — one through each side of his mouth and one through the top of his skull into his brain. At long last the would-be cop killer crumpled to the pavement.”

  8. Many “expert” shooters mock, and scorn my .50AE Desert Eagle, and I have no qualms confirming that my original decision to purchase it was based on the stated “cool” factor.

    However, since then, I have come to realize that the .50AE was not the worthless round that so many of Cooper’s disciples claim it to be, and to the contrary, I contend that a .50cal, true hollowpoint slug fired from the Desert Eagle, may be the last word in lethality.

    The .50AE sends a heavy, hollowpoint bullet downrange at almost twice the speed of sound, which means that expansion on impact is highly probable – a large part of the bullet’s energy WILL be transferred to your assailant, and drugs or not, no one hit by a slug with almost twice the energy of a .44 magnum will just “shrug it off”. At the very least, the assailant will either be dismembered, disemboweled, or thrown about violently, with the impact energy oscillating about his body like waves on a pool, rupturing blood vessels in random locations, and wreaking havoc in general. At that point, unless you, yourself are impaired, you can easily settle that gun within a second with even the slightest practice, and the second hit from one of those monsters will probably not be survivable – if the first even was.

    It’s 2016, now, and the frangible bullet has been perfected for many calibers – even the .50 caliber Action Express (using a thin, copper foil lower jacket, intended to help guard against gas port fouling). There is no longer any excuse to endanger neighbors, and family with overpenetration from excessively energetic cartridges; the frangible is ideal for home defense, and the Desert Eagle is an excellent firearm for deploying frangible bullets, given, (as with any other firearm) proper training for handling, storage, and deployment of one’s gun of choice.

  9. I need to find the right weapon and ammo that will stop a crazy person 6’4 350 pounds very strong able to pull a door off its hinges

  10. First. A miss has zero stopping power. So the first requirement is to find a weapon you can shot well – accurat fast and easy to handle.

    I see men purchase .38 Lady Siths in titanium and try to teach them to shoot. They scream drop the gun and hate it. I can’t hit a barn door with one of those. I bring over a .22 Ruger Mark III hunter with suppressor attached. They hit the bullseye mostly and find shooting fun. I have sent a lot of sheepish boyfriends and husbands to trade (no suppressor sadly)

    My point is 19 hits with a .22 beats 5 misses with a .38. Ignoring the fact that they will practice and enjoy shooting the .22

    I am talking generally about bedside guns not concealed carry though a lot of purses will hold the Ruger.

    Now let us talk tactical. I keep the suppressed.22 and a double tap loaded 10mm – just in case at my bedside. Some issues to consider. If you fire a 9 .40 or 10mm in your bedroom you and your wife will suffer d II o tlikeIpermanent hearing damage including the chance of deafness.

    If multiple bad guys enter your home and you stop the first one you will ackupboberymncertainly be temporarily deaf. The remains bad guys will know where you are and not be deaf. Not good.

    I’d rather – if I can – put 5 rounds into bad guy ones cranium and have his buddies not know. I’d like to hear the rest. And hunt them down with this advantage as we call 911

    I stuff the 10mm as backup. I want to survive with my family’s hearing intact and have the tactical advantage of them not hearing me and me hearing them. Fast or tactical mag changes help a lot.

    But at the end of the day I do have the brutal 10mm.

    Sometimes two guns are better than one. I usually carry a .40 compact or the monster 10mm

    My point is hitting the target is goal number one. So practice may be easier for small people with a .22. And that there are tactical advantages with subsonic .22 and if you can do it suppressed.

    There is no such thing as the best gun or round for every person in every situation

    I should also point out that there is no such thing as knock down power. The recoil force will always exceed the energy imparted to he target. Add to that you must penetrate enough to damage vital organs. The penetration reduces the mythical knock down power. Because it is expended penetrating. A .22 well placed will damage internal organs including the skull. At 10 yards rapid fire I put 10 rounds into one hole. With a 9mm I am happy to get most in the black. Even 5 .22 in the brain pan is more than sufficient. Shooting deer with well placed shots drops them. They are 200lbs animals.

    So don’t write of the .22. If it suits it may have accuracy and tactical advantages. Especially for smaller people.

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