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

[BCGlocker]

First, let me preface that this is not a caliber debate. Rather, it is my curiosity of the difference between three most popular calibers in self-defense.
All the recent ballistic tests showing with the modern bullet designs, the ballistic gelatin tests showing penetrations are relative similar between 9mm, 40 S&W and 45 ACP. Thus, many law-enforcement agencies are embracing the 9mm caliber.

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. So, 9mm, 40 S&W and 45 ACP all have similar penetration in ballistic gelatin (presumably in body issue), how do we account for the increase knock down power in 40 S&W and 45 ACP in self-defense shooting?

[OldMarksman]

"Knockdown power" is a myth, and differences in terminal ballistics make little difference in effectiveness.

[BCGlocker]

There is absolutely difference between the knock down power of 9mm vs. larger calibers on pepper poppers. In competition, 9mm shooters (myself included) will frequently fire several rounds at a poppers in order to get it out of way faster to have access to other targets behind it (i.e. a row of poppers or the fall of the popper that will activate a mover.

[zincwarrior]

Let me short circuit this discussion:

.45 shooters: blah blah Browning blah blah perfect gun blah blah. Consensus, just throwing a .45acp round at a car will blow the door clean off. Actually shooting it will explode a Tiger tank. 9mm aren't real bullets and can be stopped by heavy fog and are shot by plastic pea shooters.

.40 shooters: we're awesome because we have more rounds and more power. .45s are fine but too big. 9mms are ok but can't make a fist sized hole in concrete like ours can.

9mm shooters: .45s are for grandpa back when he was fighting the British in the Civil War. 9mms are cheap and we can load it on Monday and shoot it all the way to Sunday. With new ammo we're as good as .45s, right? .40s are good but they carry two rounds less than our Glockenspiel 56 which holds 97 rounds.

.357 revolver: EVERYONE else just inhales - its...a revolver shooter! Uncle Joe was right. They're...real...

10mm shooters: wimps.


EDIT: BCG-want to have fun? Hit a popper with a shotgun round. Squee!!!

[cslinger]

9mm is stopped by heavy fog.

Your work here is done sir. . That was awesome.

[stephen426]

@BCGlocker,

I think it is fairly simple if you look analyze the physics of it. E=½MV². A ballistics chart I found shows the following:

Caliber Weight (grain) Muzzle Velocity (fps) Muzzle Energy (fp)
9mm 115 1155 341
.40 S&W 180 950 361
.45 ACP 230 850 369

When it comes to shooting poppers, all of the energy is deposited into the target (since it does not penetrate the target). Poppers don't care about expansion or surface area. If you shot the same exact spot on the popper with each caliber, the one with the most energy would knock down the popper more forcefully.

Human targets are obviously much more complex and things like wound channels and sufficient penetration are factors in a bullet's effectiveness.

[K_Mac]

BCGlocker, you cannot logically or honestly claim that your post is not intended to stir the pot, while actively stirring the pot.

[doofus47]

stephen426 pretty much summed up the hard facts.

Zincwarrior wins Mr. Congeniality for putting a pretty face on the extreme sides of the caliber debate. .

[Glenn E. Meyer]

I knocked down a pepper popper with a 32 HR magnum that I was firing outlaw in an IDPA match. HOW did that happen?

[stephen426]

Originally Posted by Glenn E. Meyer

I knocked down a pepper popper with a 32 HR magnum that I was firing outlaw in an IDPA match. HOW did that happen?

Here some possibilities...

1. Someone else shot your target with a "real bullet" at the same time
2. You have magical powers
3. It was windy and the wind actually knocked it over. Your bullet just helped.
4. LUCK!

LOL

[BCGlocker]

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.

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.

[Beentown71]

The FBI has a heralded or non-sensical (pending your bias, if any) report that covers handgun calibers in shootings pretty well. Some good info in it.

Sent from my SM-G900V using Tapatalk

[DaleA]

zincwarrior--priceless!

This guy was soliciting home defense/self defense writers a while back. You might want to give him a taste of this.

https://thefiringline.com/forums/sho...d.php?t=583855

[T. O'Heir]

Pepper poppers have nothing to do with self-defence. They're shooting game targets only. Pepper poppers are 'set' by the match operators to be knocked over by whatever cartridge they feel like. Takes forever for one to go over after being hit with a cast 230 grain .45 from under 10 feet(I think it was). Isn't going to go over any faster if it was hit with a jacketed 230 either.
"Knock down" power of a particular cartridge on bad guys is a myth. No handgun cartridge has any such thing. Physics doesn't allow it. That Newton guy wrote a law about it.
"...many law-enforcement agencies are embracing the 9mm..." Everything government agencies do is about money. And rarely anything else. Police went to 9mm, 30 some years ago, because they could buy pistols that weigh less but have greater magazine capacity at prices the tax payer could afford.

[DMK]

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.

Energy may very well have an effect on a solid structure like bone.

However terminal ballistics have a lot of variables. Where it hits a person, velocity, bullet design and construction, bullet diameter, bullet weight. The latter are just two of the many variables.

Even energy itself is based on weight and velocity, not bullet diameter.

Keep in mind that two of the most historically respected handgun calibers, 45 ACP and 357 Magnum are very different. One is a slow, heavy round and the other is a very fast, light round. Both have a lot of energy.

[1-DAB]

if you miss, it doesn't matter what you are shooting. shoot the caliber that you are most accurate with under time pressure. good self defense loads all have about the same energy. i'll take more rounds on board that i also shoot better.

[zincwarrior]

if you miss, it doesn't matter what you are shooting. shoot the caliber that you are most accurate with under time pressure.

Its the simple lines that are often the most wise.

[jmr40]

Knocking down steel plates or bowling pins is irrelevant to stopping an aggressor. I can throw a baseball and knock over steel plates and bowling pins.

Stopping an aggressor involves a bullet that penetrates deep enough to reach vital organs. Bullet diameter and weight are largely unimportant and larger calibers can be a handicap. Bullets that are longer in relation to diameter tend to penetrate deeper all other things being equal.

[44 AMP]

Leaving aside real world considerations, and since all three main rounds have approximately the same amount of energy, AND that energy is more than sufficient to the task of knocking over a popper /steel plate, AND that there is NO penetration involved,..

WHY do they seem to fall faster (when it in the right spot) with bigger calibers??

I simply don't know. My GUESS is that it might be due to something I can't quantify that I'll call "dwell time" and involves momentum/inertia, not just pure ft/lbs of energy.

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.

So, I think its a matter of how much (%) is transferred DURING the time the bullet is in contact, "pushing" on the popper.

Might it not be that the larger, heavier, SLOWER moving bullets "push" LONGER even though on paper the energy level is the same???

Think of a safe door. SLAP the door, and it barely moves. PUSH the door, with a force equal to the slap, but over a longer period of time, and the door moves.

Might it be just that simple???

[Glenn E. Meyer]

Don't forget the discussion that relatively slower wadcutter 38 SPL rounds are more effective than faster hollow points (that don't expand from shorter barrels). The wadcutters cut a cleaner wound channel for more tissue damage.

This is such an old discussion.

[OldMarksman]

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.

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.

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.

[SHR970]

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.

[xnaerughiazk]

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?

[stephen426]

Originally Posted by 44 AMP

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.

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-proble...billiards.html

http://physics.bu.edu/~okctsui/PY105...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.

[2123]

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.

,