Bullet lethality: energy and velocity

[MTbackwoods]

Agreed. However, you could have a 200 grain FMJ and a 200 grain Berger VLD going the same velocity, say your 3,000 FPS. Which one will cause more tissue damage on a soft target? The VLD will based on the fact that the bullet will not only open, but it will also shed a substantial amount of it's own mass and therefore energy, into the target. That transfer of energy creates a larger permanent wound channel, a massive temporary wound channel and also disrupts more organs and tissue from the hydrostatic shock as the bullet expands and transfers it's energy. It has to be an apples to apples comparison. And a bullet is only creating a large temporary wound cavity, like the ones we see in all the slow-mo gel tests, while it is in the process of expanding. Once the bullet reaches the maximum diameter it will expand to, the temporary wound cavity collapses and the bullet continues on making a much smaller permanent wound. So a .308 bullet expands to a maximum diameter of .45. So while it is in the process of expanding, it is making a temporary wound cavity many, many times it's size. As soon as the bullet stops expanding however, it continues on making a .45" hole until it exits or loses all velocity. I'm interested in that energy dump. At what point is there not enough energy to cause rapid death? At what point is there not enough hydrostatic shock? At what point is there not enough of a temporary wound channel to create enough tissue damage to kill quickly or almost instantly?

 

[FEENIX]

In my opinion, there is not a clear 'line' of enough or too little. My rule of thumb is to have more than enough cartridge for the job. There are way too many variable involved to give you an answer. Not really sure why this is even of interest. When it comes to killing animals effectively, quickly, & humanely, it comes to shot placement and using enough cartridge and knowing the limits of your skill and your cartridge. If you are concerned about killing effect of your cartridge, you may need to get a 'bigger gun', assuming your skill level is adequate.

I agree! There are many lethality/knock down power index out there but they are simply a guide. "My" unwritten rule is 1500 FT-LBS for elk and 1000 FT-LBS for deer at point of impact and within the min velocity of the bullet to expand accordingly. The "NUT" behind the trigger remains the key factor in lethality.

 

[MTbackwoods]

In my opinion, there is not a clear 'line' of enough or too little. My rule of thumb is to have more than enough cartridge for the job. There are way too many variable involved to give you an answer. Not really sure why this is even of interest. When it comes to killing animals effectively, quickly, & humanely, it comes to shot placement and using enough cartridge and knowing the limits of your skill and your cartridge. If you are concerned about killing effect of your cartridge, you may need to get a 'bigger gun', assuming your skill level is adequate.

I have a .338 RUM as well that I'm launching the 285 ELD M at 2,900 FPS. It's more than adequate, as I think we can all agree. However, I love my 7mm. So I'll give yet another example. My ballistic calculator says that my 338 hits the velocity threshold of 1,600 FPS at 1,575 yards and the bullet still has 1,626 ft/lbs of energy. We can all agree that that is plenty of energy to be quite lethal. Now let's switch to the Nosler ABLR. If I put the 265 ABLR at a starting velocity of 2,950 FPS, which I think is a fair increase due to less weight, and trust Nosler's claim that the bullet will expand down to 1,300 FPS, I could then reliably kill at 1,850 yards where the bullet only has 984 ft/lbs of energy... if velocity is all that matters (along with bullet design) then I should be off to the races right? Both would then be equally lethal right? If energy doesn't matter then both would have the exact same effect, right?

 

[MTbackwoods]

I agree! There are many lethality/knock down power index out there but they are simply a guide. "My" unwritten rule is 1500 FT-LBS for elk and 1000 FT-LBS for deer at point of impact and within the min velocity of the bullet to expand accordingly. The "NUT" behind the trigger remains the key factor in lethality.

And I don't disagree. I know Jack O'Connor and Chuck Hawks plus many others have laid out "guidelines" for minimum energy. And I have kind of set my limits based on those energies as long as I am above my bullets minimum velocity rating. However, plenty of people have effectively taken and dropped large animals with less energy. So I am trying to seek data from people that have done exactly that and at what point have they seen diminishing returns on energy. I'm glad you agree and understand my thoughts on energy though

 

[ofbandg]

I have found energy numbers a guide and not particularly reliable. Where the animal is hit is what determines the reaction. A central nervous system hit - brain or spinal column - puts them down immediately. A hit near the brain or spine might do the same if the shock wave is substantial. A shot breaking shoulder bones anchors them. Beyond that it's about tissue disruption. Is the heart or lungs damaged and failing. They may still cover ground and travel some distance depending on the severity. I have seen large moose dropped instantly at long distance with a spine shot from a relatively light caliber and others walk away from a broadside 40 yard shot through the lungs and shoulder with a .375 H&H magnum - that didn't exit. Even a follow up shot didn't knock it over, although it finally collapsed after a couple minutes. The problems I have seen stem from the fact that the right shot with the wrong bullet sometimes works, and the wrong shot from the right bullet sometimes works, which makes it difficult to convince people to work at putting the right bullet in the right place.

 

[rammac]

Energy doesn't kill, tissue destruction caused by the velocity is what kills.
Let's say a 1lb lead ball is thrown and hits you with the SAME energy as a 200gr 30 cal bullet @ 3000fps in the chest. One you may survive, the other is very, very unlikely.

Do you see my point, energy alone imparts an impact, nothing more.
Without velocity, bullets do little damage.

Cheers.

Inaccurate and a very poor example.

The widespread myth that a bullet damages tissue in direct proportion to it's velocity still exists.

Gunshot Wounds: Management and Myths
Hanlon and Srivastava, TraumaReports, January 1, 2012

In your example the 1lb ball would have to have a velocity of around 400 FPS and at that velocity the blunt force trauma would be very deadly.

Trying to estimate what amount of energy is needed to kill is pointless, the amount needed is completely dependent upon so many factors beyond our control that it's impossible to find a specific number. A generalized value is the best that we can do and I doubt if anyone could provide a number that everyone would agree with.

 

[MTbackwoods]

You're absolutely right ofbandg. And that shock wave is what I'm referring to. I know that there is no one size fits all answer. A whitetail might soak up a round from a .50 BMG at 50 yards (I've seen the video) and an elk may drop dead in it's tracks from a .243 at 688 yards (I've seen that video too). But if we can gather the ballistic data from numerous calibers with similar bullets, I.e. Berger VLD, Hornady ELD, etc. I feel we can draw up a relatively safe conclusion based on real world data of what a minimum impact energy should be

 

[imyourhuckleberry]

I don't really think that emphasis should be placed solely on how much energy the bullet is carrying at a certain distance to make it a factor for choosing that particular round for hunting per se. I believe that you only need enough energy to carry the round the desired distance and than still have enough momentum to penetrate the target or prey in this instance. I believe this to be true , but if you do not, than explain why so many deer, elk , bears, and buffalo have been take with an arrow?

 

[MTbackwoods]

Inaccurate and a very poor example.


Gunshot Wounds: Management and Myths
Hanlon and Srivastava, TraumaReports, January 1, 2012

In your example the 1lb ball would have to have a velocity of around 400 FPS and at that velocity the blunt force trauma would be very deadly.

Trying to estimate what amount of energy is needed to kill is pointless, the amount needed is completely dependent upon so many factors beyond our control that it's impossible to find a specific number. A generalized value is the best that we can do and I doubt if anyone could provide a number that everyone would agree with.

Yes. Thank you. And you are absolutely right. Not everyone will ever agree on a specific number. Just like we will never know which is truly better between Chevy, Ford and Dodge. Too many factors are at play. However, with enough data we can find where a majority of examples prove to provide enough evidence to support a generalized number, more or less. Or maybe I'm just chasing the pot of gold at the end of the rainbow...

 

[TXAoudadKlr]

Yeah, I've been following some stuff with archery and the use of 900-1100gr arrows to punch through Cape buffalo all while packing ~80-90 FtLbs.

Sufficient weight will give the momentum to punch through if the integrity of the projectile is there!

Fluid dynamics plays a good part, main factor in why the wounds are vastly different from handgun rounds and rifle rounds. Faster bullets displace tissue more violently over slow ones.

My 300AX all but liquifies the vitals in the chest cavity where my 458 socom dispite expanding out towards an inch bores a thumb size hole typically leaving much of the surrounding tissue intact!

 

[MTbackwoods]

I don't really think that emphasis should be placed solely on how much energy the bullet is carrying at a certain distance to make it a factor for choosing that particular round for hunting per se. I believe that you only need enough energy to carry the round the desired distance and than still have enough momentum to penetrate the target or prey in this instance. I believe this to be true , but if you do not, than explain why so many deer, elk , bears, and buffalo have been take with an arrow?

I am a bow hunter as well so I understand your point. I'm not suggesting that the energy is the only or most lethal factor. Not at all. What I'm attempting to find is at what point does the energy, or lack thereof, give a general result. For example, 1,000 ft/lbs of energy has a 60% probability to shock the soft tissue and organs enough that the animal either drops or only takes a few steps whereas 900 ft/lbs only has a 40% probability of the same outcome. And that's just an example. None of those numbers are something I believe to be true. But that's kind of where I would like to end up. With a percentage of probability

 

[jpndave]

Yes I agree. I've watched and read a fair bit of his stuff. I like the cut of his jib. I thought of Broz but didn't even think about Nathan. Do you know of any of his articles or videos that speak more directly towards the thought I'm having?

This write is the best I have seen on that particular question.

Effective Game Killing

Effective game killing- How bullets kill and where to aim to ensure a fast clean kill.

www.ballisticstudies.com

 

[West Calamus]

I don't have a true opinion on the matter so please forgive me if I pry. What kind of bullets were used that dropped the elk vs the bullets used that did not? If it was the same bullet, were there exit wounds on the animals that did not drop vs the ones that did? My thought process is that if 2 bullets have identical energy of 2,000 ft/lbs, one being say an AccuBond and the other a Berger VLD. The AccuBond passes through the animal and exits the other side with 800 ft/lbs of energy left. The Berger dumps all 2,000 ft/lbs into the soft tissues and organs of the animal. Shouldn't the Berger create more temporary wound cavitation and hydrostatic shock resulting in a more likely "drop" situation? And if that were the case, at what energy level do animals tend to stop dropping on impact?

Just for sake of argument in this exercise in futility. Does the VLD really dump 2,000 foot lbs? If the VLD comes apart into smaller pieces or shrapnel can it still dump the energy as smaller projectiles versus the accubond continuing on as one solid mass. I would think mass of the object would figure in. We need a physics guru on this one.

 

[jpndave]

Lately I have done quite a bit more with old school stuff, 45-70, 44 and 357 revolvers. When you step into those and dangerous game, the equation changes a bit. They go to a flat meplat and crushing penetration rather than expansion and energy dump into the game. To stop a charge on dangerous game, especially with a handgun, you pretty much need a CNS hit. Not really the question posed her but thought I would throw that in.