Compare 9mm, 40 S&W and 45 ACP in Self-Defense Shooting?

Not saying it is impossible 9mm or smaller caliber can knock down popper; I am saying larger caliber knock the popper down with more authority. I carry both 40 and 9, so I am not arguing which caliber one should carry. Just want to know the physics of it.
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The "physics of it" takes us to Newton's Second Law of Motion: the speed with which the top, unconstrained part of the target will move will depend upon the product of the mass of the bullet and the velocity of the bullet. That's defined as momentum.

I think Stephen426's answer is what I am seeking. It seems to me it should be comparable to a punch to the popper. The heavier the punch is to the popper, the faster it will fall. I would think this heavier punch in larger caliber must have some effect on the person being shot.
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No. A 115 to 240 grain bullet will not "knock down" the person being shot. He rr she may fall, if unable to stand.

jmr40 nailed it on that.
 
OldMarksman nailed it with MOMENTUM... Momentum = mass x velocity. An Eighteen pound bowling ball moving 10 feet a second will down a pepper popper with far more authority than any of the three bullets. And we haven't even began to discuss the plastic deformation of the metal surface of the popper when hit by a speeding bullet.

ME and Momentum are like horsepower and torque. Most people focus on the first at the expense of the second. Both numbers have their place in the working world.
 
The

Eyewitness accounts describe Moros continuing to kill American soldiers with their barongs and kris after receiving multiple rounds from the .38 pistols and .30 caliber Krag rifles. Realizing the Moro was tougher than any opponent previously encountered, the Army requested guns with more “knocking power” to physically shock and immobilize their opponents.

In 1904, Brigadier General William Crozier, Chief of Army Ordnance, requested a study to determine what caliber would be best to serve this need in a new service handgun. The research led to the recommendation of a cartridge with a caliber of no less than .45.

The origin of the 45 acp? myth or legend?
 
44 AMP said:
Bullets don't penetrate the steel, nor do they fall to the ground in front of it, so clearly not every bit of their energy is transferred to the popper.
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That is not really true. If the shot is dead on perpendicular to the popper and not a angled ricochet type shot, technically the bullet has transferred all of its energy into the target. Some of the energy went into deforming the bullet, but The steel popper is transferring back into the bullet, causing it to bounce back. That is because for every action, there is a equal and opposite reaction.

If you play pool, you will understand where I am going with this. Cue balls are supposed to weigh the same as the rest of the balls. If the cue ball is hit with no spin at all and contacts another ball directly (not a glancing shot), the cue ball should stop and the momentum is transferred to the other ball. If the cue ball hits a full rack head on, it will scatter the other balls, but will get bounced back itself. The steel popper is much more massive than the bullet and will reflect the same amount of energy back.

http://www.real-world-physics-problems.com/physics-of-billiards.html

http://physics.bu.edu/~okctsui/PY105 Lecture_notes/Notes/class22_collisions.pdf

For the record, I am not saying that hitting a steel popper has the same effect as hitting a human body not am I arguing stopping power.
 
You can take all your math, physics, calculations, momentum, energy transfer, terminal ballistics, caliber, capacity, and whatever else you might want to add to this list, and send them all packing......when it comes to someone on PCP or other heavy drugs, and how they will respond to being shot.

There is no magic bullet, well, except for the .50 cal. BMG. ;)

That will get the job done, but it's not all that handy to pack around.

,
 
2123

Great post. I don't know about the 50 BMG. But I will say I've had some limited experience with a 458 Win Mag using both 500 gr. solids and soft points and PCP'ers. Not at the same time of course.
My guess is a human on PCP or not, hit solid with a soft point 458 will dance on his tip toes for about a second before he tips over.
Doesn't matter what you are shooting. Bigger is usually better.......
 
I dunno what little LE experience I have 12 gauge buck or slugs tend to be "energetic" enough to get the job done pretty much all the time and a 12 gauge is so much more portable then a Barrett. :).
 
Eyewitness accounts describe Moros continuing to kill American soldiers with their barongs and kris after receiving multiple rounds from the .38 pistols and .30 caliber Krag rifles. Realizing the Moro was tougher than any opponent previously encountered, the Army requested guns with more “knocking power” to physically shock and immobilize their opponents.

In 1904, Brigadier General William Crozier, Chief of Army Ordnance, requested a study to determine what caliber would be best to serve this need in a new service handgun. The research led to the recommendation of a cartridge with a caliber of no less than .45.

The origin of the 45 acp? myth or legend?
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We've all heard that tale, and many of us once believed it.

The .38 Long Colt was short on penetration--that was a problem with Moro garments.

The Army reintroduced the .45 Colt, and developed a new .45 cartridge for the new Model 1909 revolver.

They were about to select a new semiautomatic pistol, and the .45 ACP was specified.

None of these .45s had sufficient " 'knocking power' to physically shock and immobilize their opponents" but they fared much better against the clothing.

The Army did not return to a .45 caliber rifle.
 
@2123,

My post was made in response to 44 AMP's post about energy transfer and steel poppers, not human targets. (see the last line of my previous post)

A caliber as small and "weak" as the .22 LR to a critical part of the brain or spinal chord will drop someone like a rock. Look up how many hits have been carried out with .22s. A .50 BMG to the hand might hurt like hell, but it is highly unlikely to be fatal. That said, bullet placement is key and will have an effect as long as the bullet has sufficient penetration to vital organs.

The key to modern hollowpoints is sufficient penetration and good, consistent expansion that allows all or most of the bullet's energy to be transferred to the target. A lot of the other stuff is marketing gimmicks. For example, the sharp claws of the Black Talon "cut through flesh like a hot knife through butter". What hurts more? Getting stabbed with a sharp knife or a large spoon?
 
Holly Moly

I got side tracked on this thread. From the OP I was thinking "self defense". I posted about heavy bullets. Albeit, rifle, just to make a point. I kept reading the thread and I'm trying to figure out what a "popper" is. I had to research it to figure out what the hell it was.
Now I'm trying to figure out what the heck a popper has to do with a pooper that is trying to kill me.
Bottom line OP. As a CCW, if and when you need your weapon it will probably be needed close and fast. Pick what platform you can draw, and shoot accurately.
 
However, as all competition shooters know that when it comes down to knock down power of the pepper poppers, the larger/major caliber rounds will have more power and take down the popper faster.
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Who cares how fast the steel goes down?:rolleyes: All steel is calibrated using 9 mm. So the point you stated is mute. Some of your responses show you were not wanting to accept differing opinions. In closing it is irrelevant how fast the steel goes down.:cool: How about the shooters that are making major power factor with 9 mm??????
 
You can take all your math, physics, calculations, momentum, energy transfer, terminal ballistics, caliber, capacity, and whatever else you might want to add to this list, and send them all packing......when it comes to someone on PCP or other heavy drugs, and how they will respond to being shot.

There is no magic bullet, well, except for the .50 cal. BMG.

That will get the job done, but it's not all that handy to pack around.
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We had a stalker who was addicted to vicodin. We were advised to carry pistols with the largest caliber and capacity we could carry and have a spare mag. In light of the person, I was taught to forget "shooting until the threat stopped" and empty the mag as quickly as possible, reload and get ready to empty that mag too. We were taught the same in a house situation, but with shotguns. Yea that was a happy fun time. :(

Thats why I started competitive shooting actually.
 
zincwarrior said:
We had a stalker who was addicted to vicodin. We were advised to carry pistols with the largest caliber and capacity we could carry and have a spare mag. In light of the person, I was taught to forget "shooting until the threat stopped" and empty the mag as quickly as possible, reload and get ready to empty that mag too. We were taught the same in a house situation, but with shotguns. Yea that was a happy fun time.
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With 5 or 6 hits of 12 Gauge Buckshot rounds, I'd say there wouldn't be much left for the authorities...
 
Just on the subject as originally stated of knocking down poppers:
How about a test to see which caliber is best for knocking down those dastardly poppers.
Set the full sized popper to only fall with say a factory defensive round of 230 grain .45acp.
Then try various loads and bullets of the three calibers to find out if there's any difference.
A guess would be velocity and bullet weight, along with accuracy, makes more of a difference than caliber.
 
The heavier the punch is to the popper, the faster it will fall. I would think this heavier punch in larger caliber must have some effect on the person being shot.
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Yep, but there is whole world of disagreement on how much. Given a choice on targets that shoot back, I'll always take the biggest round that I can handle and tote around conveniently, and conceal for every day work...and that'd be...ta da...the .45.

if you miss, it doesn't matter what you are shooting.
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Hmmm, some of the fire balls I've seen emerging from my Model 19 .357 at dusk, would have incinerated the target at bad breath distance...just sayin'

YMMV, Rod
 
My 22 Mag NAA mini revolver lets out a giant fireball and sounds like the wrath of God. When I shot it between partitions at a range, the blast blew my hair back and went under my shooting glasses. That's stopping power! :eek:
 
Just for the record, I'd never want to be shot with a .50 cal. BMG, anywhere on my body.

That round tends to tear your limbs off if it hits one. :(

Some years ago, I had heard that the .22LR round has killed more people in the USA than ALL other calibers combined.
 
barongs and kris after receiving multiple rounds from the .38 pistols and .30 caliber Krag rifles.

Can we say that the 30 krag round would not penetrate their clothing?

Was the move to a 45 round just typical generals fighting the last war?

I suspect there was validity to going to the 45. I own more 9s than 45s, but just reloading for them show quite a difference. Is the 9 more efficient than the 45, probably, but only recently with new bullets, otherwise its just a 355 hole vs a 451 hole or a 308 hole.
 
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Maybe for basic ball, the larger caliber has the better performance but who shoots ball for self-defense?

Personally, I look for real-world results. After extensive studies, they found most of the self-defense sized cartridges, from 9mm to 45 ACP, have about the same one-shot stop outcomes. All are in the 32% - 35% range. So carry what you are comfortable shooting.

I, too have heard that 22 has killed more people than anything else. Probably due to a) ubiquity, more 22 guns than anything else by a wide margin and b) it's been around forever. I'd also suspect a lot of those are suicides.
 
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