Can someone explain terminal ballistics to me? People say that rifles wreck people because of their velocity...

Yes. Also big heavy projectiles drag a bunch of clothing and derbies into the wound. Since medicine sucked back then and people wore shit-caked rags the rate of deadly infections and gangrene was incredibly high.
So even if you survived the shot and didn't die from blood loss you were likely to be killed a week later by the infection.
That's why civil-war doctors were so eager to get down to business with the amputation saw, it lowered the risk of deadly infections at the cost of a limb or two.

Yes. Same with pistols and big bore air rifles. "Rifle-like" wounding (i.e., exploded tissue) starts above 2100-2200 FPS.

"Bruh, I grafted volley sights from a Lee Metford onto my 870. Watch me take out this deer with a forester slug at 400 yards."

Yes. black powder has a fairly hard limit on velocity. You can't make it go much faster, so if you want it more powerful your only real recourse is to make bullets bigger.

Absoloutely true.

There are lots of other trade-offs as well. For example, smaller faster rounds take up less space and weight than big fat heavy ones do.

unironically based and redneckpilled

I could get reliable hits on a deer target with slugs out to about 250 yards. Past that and the drop is so much you have to essentially mortar your shots in.

It's a good technique when the deer have belt armor but no deck armor.

OK wound physics 101.

Momentum vectors. When a projectile impacts water they transfer forward momentum into sideways/spherical momentum of the expanding air bubble. This movement stretches epithelial tissues which tear, causing damage and bleeding. Epithelial tissue is the shit that holds all your organs together and your blood vessels too.
Thats momentum, kinetic energy comes into it when we see how much kinetic energy it takes to tear a piece of epithelial tissue, which is averaged at 1kJ. It has a large lower energy variance depending on how many layers the tissue has, if its cuboidal (bladder) or something else. But 1kJ kinetic is the rule of thumb for skin, same for thermal laser energy which is a weird coincidence. Without that level of energy its impossible to see the kind of torn skin exit wound common in rifle ammo hits.
Shape of the projectile determines how easily momentum vectors change, how much energy is deposited in the body itself, and how much leaves the body through exit wounds to be wasted on air and backstop.

There you have it, energy controls damage available, round shape/momentum controls damage deposited.

>The year of our lord 2019
>Not using a Top-Attack guided anti-tank missile,STRIX mortar round, or anti-tank ground attack aircraft to target the vulnerable soft spot on whitetail deer with 120mm of RHA and ERA on the bow and sides

This would be so fun to ring steel with. Thankyou based fuddposter.

The bullet of a 5.56x45 usually weighs between 55 and 77 grains and has a velocity of 2700 to 3100 fps in order to deliver enough force to be lethal.

.45-70 typically has a bullet weight between 300 and 500 grains which is why it's lethal as fuck going only 1300 fps.

I've got to try this shit!

Attached: slugs.png (880x662, 58K)

High velocity rifle rounds transfer their energy more efficiently due to fragmentation or tumbling. 223 is superior to 45-70 because of this and is more lethal.
45-70 is going to be a lot better for large game where you need momentum and to have the projectile stay intact to reach vitals.

Energy deposited over time and area.

>High velocity rifle rounds transfer their energy more efficiently due to fragmentation or tumbling. 223 is superior to 45-70 because of this and is more lethal.
No user, that's fucking dumb.

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>Can someone explain terminal ballistics to me?
Terminal ballistics is not derivable from first principles. It's an unholy combination of fluid mechanics, rigid body mechanics, non-rigid, and materials science. You can say some very broad things like destroying tissue requires work, so a projectile need kinetic energy. Also to destroy more tissue a projectile needs penetration, which requires momentum. You can also argue from geometry that a large cross sectional area would destroy more tissue, so you want a large bullet, or one that mushrooms on impact like a hollow point, or fragments.

So I can confidently say a large, heavy, fast projectile kills gooder.

But in the real world we need to compromise. You can have a 1 kg, 1 bore copper solid, going 5000 m/s, because somebody has to carry the thing that shoots it.

So given a set of constraints, how to you pick what mass, velocity, caliber, and bullet construction to go with? No one can solve that problem on paper, it's too hard a math problem. The best we can do it shoot a bunch of shit with a bunch if different bullets and see what happens. Over time we develop an intuition for what ammo to use where.

>Also lots of energy transfer
Having a bullet stopped by a bullet proof vest means a higher (100%) energy transfer than having the same bullet punch right through you. Since the best makes you less likely to be killed, energy transfer is obviously bullshit.

> It's like the difference between your car getting getting hit by a bicyclist going 40mph, and a 60ton semi-truck going 20mph.
Right, so you took the old analogue usually used to explain the difference between kinetic energy and momentum, then you fucked up the example so it no longer shows that (as the truck has much more of both) and finally you went and claimed it showed the effect of energy instead of the effect of momentum since you don't know what momentum is.

So OP, if you think the whole thing seems very hard to grasp, there's the reason for it. A lot of people try to explain things who were never taught even half of the physics necessary to explain impacts and penetration, and they don't remember even half of what they were taught either. And so you get people like flailing around trying to make the one thing they remember relevant, like someone trying to cut steak with his eyelids because he has forgotten he has a mouth and has never been shown a knife if the first place.

If you want to not be someone like that, go brush up on your physics until you at the leats have a good grasp on momentum, impulse, can understand Wikipedia's paragraph on Newton's impact depth estimate and have some idea of how drag works.

>Since the best makes you less likely to be killed, energy transfer is obviously bullshit.
Take a shotgun slug to the vest and tell me energy transfer doesn't cause trauma faggot. I'll supply the vest and the slug, you just have to stand there.

A punch never penetrated anybody either. They still can kill you. In your rush to show off you wound up even more retarded.

The point is a slug that pancakes on body armor dumps more energy than one that passes through your chest, but is less likely to kill.

And a slug impacting a kevlar vest dumps the same amount of energy, and still kills you even though it stops the slug.

Armor doesn't change the force equation, it changes what it happens to.

>how the big, heavy rounds like .45-70, .44 Magnum, or shotgun slugs kill when they're not going very fast?

the same way you can be killed by getting punched in the head from a distance of 0-1 feet

human bodies are bags of meat and juice, they are not bulletproof (or even fistproof)

So "less likely to be killed" is now the same as "no trauma"? What a very special way of looking at things. True to character I guess, as it's just like your take on physics. Also what you are saying here (probably without realising it yourself) is the trauma caused by the slug being stopped by the vest is somehow more lethal than the trauma caused by the slug punching right through you and carrying on. Stopping means full energy transfer, carrying on means less than full energy transfer. So if energy transfer is what harms, then you would be worse off with the vest there than without it. You wouldn't happen to be a fan of Jodorowsky?

Now then, wanna do some energy transfer calculations?
Take a cup of coffee, say 0.2kg/7oz of liquid. Make it 67°C/153°F warm, not exactly scalding. Drink that. As it's 30 Kelvin hotter than your guts, you just transferred roughly 30*4.18*200 = 25kJ of energy right into your guts. That'll make a .50 BMG shot look anemic. So counting joules transferred remains absolute rubbish for predicting damage done. Which I guess is why we talk about blunt force trauma and indentation depths when it comes to the damage done through vests rather than energy transferred. Actual tissue crushed is what counts, not energy transferred, because the energy can just end up as harmless heat (no bullet of interest here has enough energy to cause significant burns this way) instead of actually doing anything.

Lol

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ke=1)2m•v^2
f=m•a

Is there any reason not to go with big and heavy bullets today if your shooting's going to be confined to the indoors?

Christ and here I thought I was dealing with first day of highschool physics, looks like we're doing physics 101 instead. If you're done sucking your own dick.

Name one (1) way to practically calculate trauma of a bullet pls.

Your advice to
>If you want to not be someone like that, go brush up on your physics until you at the leats have a good grasp on momentum, impulse, can understand Wikipedia's paragraph on Newton's impact depth estimate and have some idea of how drag works.
Is 110% worthless in every practical sense.

To approximate trauma caused by a bullet, you can pretty much only rely on its muzzle velocity and then look into the specific characteristics the bullet type used has after impact.

The thing about physics is that simply knowing the formulas won't get you anywhere, the hard and useful part is knowing what they mean and how to use them. Have fun trying to how far a flashlight will illuminate things for you simply by looking up Maxwell's equations. You won't know what the fuck any of them means and it's a problem you should be approaching experimentally anyway.

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Recoil, mag capacity

Oh, so this is what you have a problem with, not the guy who thinks joules dumped is how to calculate the injury and that bullet proof vests at best do nothing to keep you alive? Nope the guy who keeps telling him that it ain't that fucking simple is the problem. Why the fuck do you think I haven't just slapped the guy across the face with the proper physical way of calculating injury? You'd think that'd be an easy way to go about it if such existed.

>Is 110% worthless in every practical sense.
No, it'll inoculate him against nonsense the like energy dump and "stopping power" formulas.

> you can pretty much only rely on its muzzle velocity
I'd say add the bullet mass to the approximate qualitative lineup, given the correlation between penetration depth and momentum.

So much bad information ITT
Shot placement is king
penetration is king
Big holes to let blood out is a distant 3rd place.

Energy transfer is irrelevant
Temporary cavities are irrelevant
Bullet fragmentation is not desirable
Stopping power is a myth.

Read and learn

gundata.org/images/fbi-handgun-ballistics.pdf

In simple terms, its all about energy transfer. I will make up math to explain

>Mass×velocity=energy
SO
Bullet×Speed=Ouch
How does a heavier, slower bullet still kill? Lets break it down, lets say 10 is the number that needs to reach for enough ouch to kill
So, small bullet, SpeedyFast is
>2×5=10
Bam, kill
Heavy bullet, slow is
>5×2=10
Still kill
If you decrease one, you can increase the other to compensate

Mass times velocity is momentum, not energy.

Do some not made up math, calculate the momentum of a major league fastball, and a .45 ACP fmj bullet. Which one is more likely to kill?

Sure but it works for simple picturing
Now we're getting into surface area and psi exerted, plus material of the projectile

>Now we're getting into surface area and psi exerted, plus material of the projectile
Exactly my point.

>large calibers rely on expansion force to deal damage relying on mass.

>intermediate calibers use moderation

>small calibers rely on fragmentation.

large is relative a .22LR, .357, .45, 12 guage slug use their weight as the primary driving force, the use of expansion force is common for pistol calibers

the .223, 5.45 (Russian), and .280 British rely on fragmentation.

the .17 HMR, 9mm, 7.62 (NATO and Russian), and .50 BMG use a mix of both.

a hollow point transfers velocity into expansion force.

a boat tail transfer velocity into range and penetration

a jacketed hollow, "rip", or shot round transfer energy into fragmentation.

>Temporary cavities are irrelevant
But but but it looks so impressive in the high speed photographs!

>Mass×velocity=energy
Fucking hell

>the use of expansion force
I've heard of speed force, but what superhero uses expansion force and is it just as stupid a plot device?

>transfer energy into
Man you're going to have your mind blown when you discover friction.

based and bubbapilled

>>all about energy transfer.
Nice troll

What a load of crap. Admit it, you’re just pulling crap out of your ass. Learn

Shot placement
Penetration
Big holes.

>John T. Thompson

he used the reliable description of scientific information by shooting the shit out of an animal carcass to get the US military to adopt his machinegun.

friction is but one description of the transfer of energy and it may be transferred via multiple methods, including elastic and non-elastic collision, thermal, electromagnetic, gravitational, strong nuclear, and small nuclear.

where in expansion for is a technical description for a very specific kinetic reaction of a soft body solid as defined by classical physics, often referred to as practical physics.

>The year of our lord 2019
>not using Betty Lou, a combination AK-57 uzi radar laser triple-barrel
double-scoped heat-seakin shotgun

this is all the nessary experimentation to make the biggest, deepest whole, in the exact place that I want them.

>like your whore of a mother.

You are not going to get a good explanation here. Look at the writings of Elmer Keith and W.D.M Bell. Then look at the opinions of weatherby and Jack O'connor. That will catch you right up.
Task at hand should dictate if you need what boils down to speed or weight.

You can have a bullet that is small enough in size and moving fast that dumps all its energy in a thin skinned target. The temporary cavity will cause enough damage the animal is DRT. The same round on a bigger or thicker skinned animal will "dump" its energy too soon. It will never reach the vitals and the temporary cavity will not effect the animal in a way that causes death. That same animal shot with a much larger round going slow, think 2100fps will be completely passed through by the bullet and even bone.
The wound channel will be minimal.
"Eat right up to the hole" as opposed to "holy shit where did it's shoulders go?"

The morons keep coming
You are just puking back what some idiot at the gun store told you.

ReadKinetic energy does not wound. Temporary cavity does not wound. The much discussed "shock" of bullet impact is a fable and "knock down" power is a myth. The critical element is penetration. The bullet must pass through the large, blood bearing organs and be of sufficient diameter to promote rapid bleeding. Penetration less than 12 inches is too little, and, in the words of two of the participants in the 1987 Wound Ballistics Workshop, "too little penetration will get you killed."42, 43 Given desirable and reliable penetration, the only way to increase bullet effectiveness is to increase the severity of the wound by increasing the size of hole made by the bullet. Any bullet which will not penetrate through vital organs from less than optimal angles is not acceptable. Of those that will penetrate, the edge is always with the bigger bullet.

Rifles typically deliver enough energy to tear wound cavities open with shock waves
Slower, larger projectiles are less effective, but can still kill because a high enough amount of bullet holes, or ones in the right places are going to kill somebody eventually.

To generate energy you have to increase the mass of a moving object, increase the velocity of a moving object, or increase both. However there is a break point when it comes to rounds where you are trying to achieve the most amount of energy over the longest distance while having the least amount of recoil. In previous centuries this could really only be achieved by increasing the mass of a bullet because they either hadn't figure out how to create a higher velocity round or didin't have the science to create the round or a sufficient weapon to put it into. This is why bullets because higher velocity over time and sacrificed weight, the science made it possible to create weapons to fire it and to allow the creation of the wound in the first place.

The temporary cavity is literally the tearing of tissue. It is the destruction of the capillary and arteries in the area.
You couldn't possibly be this stupid.
You could kill a person blasting air through them. Holy fuck you are dumb.

Wow. Bullets and Arrows kill in different ways because of energy dump. Literally. An arrow kills by blood loss. A bullet can kill that way, buy it is the massive trauma that allows a bullet to drop an animal in its tracks.
Someone could walk up to you and push a pencil through your leg. The damage would pale in comparison to a round of the same size fired at high speed. The bullet injures twice. Once as it passes through, and once as it rapidly transfers its energy into the animal causing massive wounding.

> the impairment of kinetic force to the displacement of organs and other soft body material until the body is unable to function and ceases living.

all rounds provide able force to perform this effect, but the experimentation has found several acceptable solutions of varying application.

the use of "knockdown" power is the application as a kinetic reaction, not to cause fatality, but to prevent mobility, or to maintain sufficient kenetic potential to impart the necessary kinetic force to result in a fatality.

the penetration of vital organs is not necessary, only the rupturing of critical tissue so as to prevent their function.

based on the effectiveness of shot placement this may or may not be a quick process. but you can supplement shot placement by volume of destructive force such as with a larger round or multiple rounds.

Think of a .556 as lobbing a rock through someones temple with a small stone from a slingshot.

Think of a 12g slug as just smashing that person's head with a brick.

>The temporary cavity is literally the tearing of tissue.
Most tissues are highly elastic, meaning you can have a very big temporary cavity without causing any injury. There's also the question of how big and scary looking a temporary cavity you get in gel that's mostly just meant to provide a common comparison of penetration depth.

>No one can solve that problem on paper, it's too hard a math problem.
I don’t believe you.

Jow Forums at its best

This anonIs quoting the FBI handgun wounding study and he also posted a link to that study. HereBut youYou are so smart, you know more than the FBI, more than the pathologists involved in the studies, more than the surgeons and Emergency Room doctor.
Please don’t breed any stupid children, Confirmed for idiot

The same with you.
You must be smart.
seeDumbass

Psychological factors such as energy deposit, momentum transfer, size of temporary cavity or calculations such as the RII are irrelevant or erroneous. The impact of the bullet upon the body is no more than the recoil of the weapon. The ratio of bullet mass to target mass is too extreme.
The often referred to "knock-down power" implies the ability of a bullet to move its target. This is nothing more than momentum of the bullet. It is the transfer of momentum that will cause a target to move in response to the blow received. "Isaac Newton proved this to be the case mathematically in the 17th Century, and Benjamin Robins verified it experimentally through the invention and use of the ballistic pendulum to determine muzzle velocity by measurement of the pendulum motion."29
Goddard amply proves the fallacy of "knock-down power" by calculating the heights (and resultant velocities) from which a one pound weight and a ten pound weight must be dropped to equal the momentum of 9mm and .45ACP projectiles at muzzle velocities, respectively. The results are revealing. In order to equal the impact of a 9mm bullet at its muzzle velocity, a one pound weight must be dropped from a height of 5.96 feet, achieving a velocity of 19.6 fps. To equal the impact of a .45ACP bullet, the one pound weight needs a velocity of 27.1 fps and must be dropped from a height of 11.4 feet. A ten pound weight equals the impact of a 9mm bullet when dropped from a height of 0.72 inches (velocity attained is 1.96 fps), and equals the impact of a .45 when dropped from 1.37 inches (achieving a velocity of 2.71 fps).30
A bullet simply cannot knock a man down. If it had the energy to do so, then equal energy would be applied against the shooter and he too would be knocked down. This is simple physics, and has been known for hundreds of years.31 The amount of energy deposited in the body by a bullet is approximately equivalent to being hit with a baseball.

huh

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Not that user; from one point of view you could construe it as too hard, though it is better to simply say that this problem has no closed-form solution. The overwhelming majority of problems we attempt to solve fall under this class of problems, where we're forced to reason inductively and make probabilistic assertions.

The advent of modern simulation techniques will enable us to really start making interesting headway into these types of complex phenomena, but for now we are somewhat relegated to these imperfect ways of assessing terminal ballistics, where consistency in ballistic gelatins (and meeting various performance parameters in testing using gelatin) has to act as a sort of proxy for multiple layers/layouts of tissues of different properties with a non-Newtonian liquid flowing through them.

If we talk about something like kinetic energy and fast bullets, then we can sort of understand how this relates to exceeding tissue elasticity tolerances, but even there we are forced to stop because propagation of energy in such a non-uniformly constructed environment is not presently solvable in the deductive sense. We know it's not good but I can't construct that system of equations and tell you what's going to happen to the game degree of mathematical precision that I (or anyone else who does that kind of thing) would usually desire.

This field ("terminal ballistics") will only start to solve the really fundamental problems this thread brings up when it starts approaching the problem with scientific rigor (I suspect this will be when proper armors finally begin to be fielded). For now, we can only really confidently say that there is an objective difference in soft tissue wound severity with high speed projectiles, and the human body is not a sufficiently durable medium to coax out any more interesting aspects of the problem.

One quibble, the MOMENTUM absorbed by the shooter and the target are the same. The change in momentum is force integrated over time, and the force of the expanding gases acts on the bullet and the gun for exactly the same time, so the magnitude of the momentum is the same.

But the ENERGY absorbed by the shooter and the target are not the same. The bullet has less mass than the gun+shooter, so when the expanding gases push with equal but opposite force on the gun and the bullet the bullet accelerates more, and work (change in kinetic energy) is force integrated over distance, so the bullet gets more energy from the expanding gases than the shooter does.

Bruh Momentum

one thing to note is mechanical advantages. the shooter feels shock dispersed through a rifle stock. the target feels one consolidated punch from the round. the surface area matters- but you are right in a sense, the bullet isnt literally gonna knock a guy over and fuck him up solely due to mass lmfao. they could be similar

It's nothing like getting hit with a baseball. It's like having a straw jammed in you and then having a pocket of air violently expanding inside you and then slamming shut. That causes massive damage. It's a fact that can visually seen in ammo tests and replicated and captured on high speed cameras with a human analog, and has. You are trying disprove what at this point has been proven to the point it is common knowledge.

One can even see it in meat around the bullet wound on a deer. A 44 makes a small wound with little damage.
A 270 destroys all the meat it touches. It becomes a nasty coagulated mess temporary wound channel causes permanent and massive tissues damage. That is physically traumatizing.

everyone needs to understand that the paper linked is specifically talking about handgun rounds.

"The tissue disruption caused by a handgun bullet is limited to two mechanisms. The first, or crush mechanism is the hole the bullet makes passing through the tissue. The second, or stretch mechanism is the temporary cavity formed by the tissues being driven outward in a radial direction away from the path of the bullet. Of the two, the crush mechanism, the result of penetration and permanent cavity, is the only handgun wounding mechanism which damages tissue"

"Temporary cavitation is nothing more than a stretch of the tissues, generally no larger than 10 times the bullet diameter (in handgun calibers), and elastic tissues sustain little, if any, residual damage."

the whole point of this thread is 's question about the difference between terminal ballistics between rifles and larger slower rounds.

A rifles bullet is moving so fucking fast that it DOES push shit out of the way so fast and so far that it destroys tissues that may have been 3 or 4 inches away from the initial entrance of the bullet. In anywhere in the chest, this will completely destroy at least 1 lungs functionality and has an extremely high likelihood of rupturing the heart.
HANDGUNS are a completely different story because they aren't moving fast enough, as i quote above 'handgun bullets generally cause a temporary cavity no larger than 10 times the bullets diameter' and usually the speed and distance at which the tissues move are not fast enough to significantly cause damage. As such the only reliable way for handgun (and subsequently other large, slow projectiles such as the ones op listed) is by the crushing force and permanent cavity.

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For handguns and other larger slower projectiles that can't capitalize on the hydrostatic shock like rifles, you want to maximize the crushing force of the bullet, this is done by getting a bigger bullet, or getting a bullet that expands upon impact like soft point or hollow point bullets. You need to create a wound channel that physically penetrates vital tissues.

Also from this is probably the most important takeaway.

"Physiologically, a determined adversary can be stopped reliably and immediately only by a shot that disrupts the brain or upper spinal cord. Failing a hit to the central nervous system, massive bleeding from holes in the heart or major blood vessels of the torso causing circulatory collapse is the only other way to force incapacitation upon an adversary, and this takes time. For example, there is sufficient oxygen within the brain to support full, voluntary action for 10-15 seconds after the heart has been destroyed.28
In fact, physiological factors may actually play a relatively minor role in achieving rapid incapacitation. Barring central nervous system hits, there is no physiological reason for an individual to be incapacitated by even a fatal wound, until blood loss is sufficient to drop blood pressure and/or the brain is deprived of oxygen. The effects of pain, which could contribute greatly to incapacitation, are commonly delayed in the aftermath of serious injury such as a gunshot wound."

Best post I’ve ever seen on this shit forum. Good job.

Why simulate when you can just shoot a few hundred pigs and see what happens?

Jow Forums isn't a forum you dumb fuck.

>bromentum

Thanks very simple

>Momentum vectors. When a projectile impacts water they transfer forward momentum into sideways/spherical momentum of the expanding air bubble. This movement stretches epithelial tissues which tear, causing damage and bleeding. Epithelial tissue is the shit that holds all your organs together and your blood vessels too.
>Thats momentum

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What's the problem? We learn about momentum vectors from the pool example in high school, it's basically the same thing.

Spherical momentum is not a thing.

1. Those 11mm big bore rounds are shot at close rifle ranges. Most situations described as a defensive encounter are less than 25 meters. The volume of the rounds pan out on impact, and therefore cause a lot of damage.

2. Higher velocity 7mm rounds ether pass though or cause just as much damage when distances are greater do to hemorrhaging. Lighter 5mm or equivalent rounds are unpredictable on impact with losing energy, creating wounding vectors that can not be diagnosed or treated.

3. Depends on how big the hole and where.

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user you realize vectors can be three dimensional?

> vectors can be three dimensional
No shit, sherlock.

The constraint on momentum is that the vector sum is conserved. If the bullet comes in horizontally then the momentum of of the matter deflected up has to be equal in magnitude to the momentum of the matter deflected down That's not enough to infer the amount of deflection. Any amount of deflection, as long as it is equal, is consistent with conservation of momentum.

Even in the direction of bullet travel you can't calculate damage from momentum alone. Newton's 3rd law says the force applied by the bullet to the tissue is equal and opposite the force applied by the tissue on the bullet. Calculating that force from first principles is not practicable. If we make a simplifying assumption about the force, all you get is the time it takes for the bullet to come to rest, because integrating force over time gives you delta p.

To get the distance the bullet travels, or the amount the tissue stretches you need the force applied by the tissue and the mass of the bullet. Formulating the problem that way is equivalent to working it out by the kinetic energy.

>forum

>You can have a 1 kg, 1 bore copper solid, going 5000 m/s, because somebody has to carry the thing that shoots it.
So, you neck a 105mm shell down to 40mm, load a 40mm copper solid over a couple of pounds of IMR 4065. Slap a 40mm liner into a 105 barrel, there ya go. Bren carrier provides all of the mobility you need. All of these problems have been solved long before we were born, user. Don’t make this any more difficult than it needs yo be.

It's energy and momentum competing. .223 has a good amount of energy, but without much mass it doesn't have a ton of momentum. Without momentum it doesn't carry through the target, it breaks apart and transfers all its energy. Even if it does manage to stick together it can be deflected as it travels through a body.

Heavy rounds have extra mass for more momentum. As long as the bullet can stay together, the momentum will carry it deeper and deeper through tissue, bone, etc.

So big heavy rounds tend to be pretty good for big animals when you need to carry a round through a lot of tissue and viscera to get to an important organ. The need for very deep penetration is also why you'll see different alloys for a harder projectile that guarantee it doesn't break apart into small fragments that lose momentum quickly.

People aren't all that big, so lighter, faster rounds that can dump energy fast work well on us. A .223 zipping along at top speed fragment on impact and effectively explode as flesh tries to slow the projectile down, since our organs aren't all that deep, that leads to quick and reliable trauma. Speed also tends to defeat armor, so an extra bonus there.

So the tl;dr here is that if all materials are equal, small, fast, high energy rounds do huge damage when you don't need to hit too deep. If you're hitting a target that has a lot of flesh between its skin and its important organs, you'll want something big, heavy, and with a lot of momentum. "Exotic" (non-lead) material projectiles change this a bit, but that's the basics.

is that why something like .44 Magnum works better against animals than people?

Here's your lord and saviour LTC Art Alphin
youtube.com/watch?v=mY-sXAF8Llo&list=PLYfWRNnbeXlNVUC8gBypKoxxSK8_bV5Ot&index=14&t=0s
He estimates terminal effect as a function of bullet velocity and cross sectional area

Just a caveat: this applies only if the bullets have a similar air resistance. A low-drag, light bullet can outperform a high-drag heavy one.

Kinetic Energy(Ke)=(1/2)M*V^2. Thus for every change in mass you get a (comparatively) small change in kinetic energy. However, for every change in velocity there is more kinetic energy because of the squared term. Ke is what does damage but there is a limit to the amount of energy you can pump into a small mass. After a certain point there is diminishing returns. Additionally, because of the law of conservation of momentum (Momentum (L)=M*V) larger masses tend to hold their energy longer. This is why your ultra long sniper shots areally done with heavy AND fast calibers. Holding energy longer = more stable flight time and longer range lethality.
Any questions?

Also as a brush gun, big heavy bullets don’t get as effected by leaves/twigs

.45 SMGs could work.

most trucks are

Depends on the country son. By international standards US trucks haul small loads.