Bullet Energy

[0ne3]

I, read some place that a bullet should have ??? energy, when it strikes the target. At what energy do we need for deer? Does any one know? Thank You

 

[FL-NC]

I too would like to know who came up with whatever numbers are preached on this subject, and when, and why. As for me, I routinely kill deer very efficiently with rounds like 223 in a 75 grain OTM, and I killed on thanksgiving with 300 BLK subsonic in 190 grain. According to the internet, these are insufficient.

 

[WestKentucky]

Here we go again...

It takes very little energy to perforate a deer. It has been done for centuries with a very simple, relatively weak bow with a big heavy arrow. It takes multiple skill sets to do this.

With a rifle you get a lot more energy in a more controlled energy dispenser that takes a lot less skill to operate. Even the lowly 22lr has ample energy to drop a deer, and 22lr is widely claimed to be the poachers choice. Moving up from 22 just gets you more efficient.

 

[WestKentucky]

I too would like to know who came up with whatever numbers are preached on this subject, and when, and why. As for me, I routinely kill deer very efficiently with rounds like 223 in a 75 grain OTM, and I killed on thanksgiving with 300 BLK subsonic in 190 grain. According to the internet, these are insufficient.

What I love is this... you throw down both ends of the spectrum. 30 cal heavy slow, and small fast. Both work well, but then again so do things a lot bigger and badder. Different mechanisms though which are somewhat mutually exclusive. It’s hard to get the penetration and expansion of a heavy slow with anything fast because it disentigrates on impact. It’s hard to get the devastating explosive damage of a light fast round puts on whatever it hits because extreme fragmentation requires a lot of speed.

 

[Laphroaig]

I've always heard that the rule of thumb is 1000 ft-lbs. for deer and 1500 for elk. But as others have stated, kinetic energy is only one factor to consider.

 

[horsey300]

I, read some place that a bullet should have ??? energy, when it strikes the target. At what energy do we need for deer? Does any one know? Thank You

In my state, you must fire a .22 or larger projectile carrying 900 ft lbs to 100 yds in a rifle, i forget the handgun rules specifically but essentially anything with less energy than a hot 158 .357 at 50 yds is illegal. Some states differ greatly to either end of the spectrum. Energy is used to knock elephants out. Everything else is killed with shot placement, bullet construction, and velocity windows. In that order.

 

[jmr40]

Ever since gunpowder was invented people have tried to come up with a mathematical method to predict how effective various firearms are. Using energy numbers is probably the best of those methods, but is still a poor indicator. Traditionally 1000 ft lbs energy has been the number I've seen thrown around for deer or black bear and about 1500 ft lbs for elk, moose, or big bear. But all of those animals have been taken with guns, or arrows with far less energy.

You need a bullet with enough mass, and the right construction to ensure adequate penetration on the game hunted. And deer don't need anything special. Most any 100 gr bullet, and some much lighter will give plenty of penetration on deer. Then the bullet needs to impact with enough velocity to expand. That number is usually between about 1800-2800 fps. Slower than 1800 and many won't expand, faster than about 2800 and many over expand and don't penetrate. It varies by the construction of the individual bullet and some will work at slower impact speeds, others will stay together at well over 3000 fps. But if you choose a bullet that will stay together at 3000+ fps, it needs more speed on the low end to expand. One that expands well below 1800 fps will blow up below 2800 fps. And of course shot placement trumps everything.

Using energy numbers CAN predict how well bullets expand and penetrate as long as all of the above criteria are met. But it is possible to get misleading information. When you double bullet weight energy numbers double if velocity stays the same. But if you double bullet speed then energy numbers quadruple if weight stays the same. The math formula is biased toward speed more than weight. Yet bullet weight is what gives you penetration and too much speed limits penetration.

 

[CraigC]

Energy is a meaningless number, only useful as a marketing tool to sell velocity. We'd all be better off if it was never mentioned again. It is not and never was a proper gauge of a cartridge's effectiveness. The problem here is that people 'need' a simple way to compare one to another but energy is a simple (and wrong) answer to a VERY complicated question.

 

[cheygriz]

Energy is a meaningless number, only useful as a marketing tool to sell velocity. We'd all be better off if it was never mentioned again. It is not and never was a proper gauge of a cartridge's effectiveness. The problem here is that people 'need' a simple way to compare one to another but energy is a simple (and wrong) answer to a VERY complicated question.

Energy is not the magic measure, but it beats the silly notion of momentum.

 

[CraigC]

Energy is not only less than useless, it creates a good many misconceptions. Momentum is at least a factor in penetration.

 

[Bfh_auto]

There was a thread about someone killing a deer with a pellet gun.
It takes a lot less than people think.
It's more about do you want a blood trail or not.

 

[brewer12345]

My state requires 1000 ft l at 100 yards for big game. Yet they also allow you to take the same animals with a bow, crossbow, handgun (500 ft lb required at 50 yards), and muzzleloaders (50 cal min for round ball for deer). Ignoring the bow options, it isn't hard to see that energy requirements are nonsense given the varying energy levels required for rifle and handgun and the typical energy developed by a 50 cal roundball load with black powder.

 

[Varminterror]

It’s pretty hard to say Kinetic Energy is useless/meaningless, since it’s only made up of bullet weight and velocity. Can’t really deny ANY ballistic metric has to incorporate one or both of those. If I throw a 500grn, 50 cal bullet by hand, it won’t penetrate much, as the velocity is too low. If I shoot a sewing needle at 4000fps, I bet it doesn’t kill well either, since it has too low bullet weight and too small of diameter.

Projectile weight, profile, density, and velocity are really all we have to go by, and Kinetic Energy depends upon the two more important of these. It’s fair to say KE means far less in an inelastic collision than momentum, but momentum is also based wholly and solely upon velocity and bullet weight.

The real trick: any one metric likely doesn’t paint a sufficient picture to compare dissimilar cartridges.

 

[brewer12345]

This has been debated to death. Where I come out is that a projectile with the mass and speed to reach the vitals and do major damage/make big holes is what is necessary.

 

[mustanger98]

And another guy had a thread on here... he was killing deer with, IIRC, a .38-40 with a cast lead bullet and described complete pass-throughs. All it has to do, in reality, is destroy the vitals. But that's for states where bullets that don't necessarily expand are completely legal.

Of the deer I've harvested so far, I haven't recovered a bullet. So regardless of published numbers about energy at whatever speed, I don't know what they're doing besides penetrating and destroying the vitals.

 

[Dibbs]

Energy is not the magic measure, but it beats the silly notion of momentum.

IMO, you can use these ME and MV #s as standards of comparison, but there simply is no "magic bullet".

An interesting concept I heard of a while back is that if you hit the animal thru or near the vitals
at the "upstroke" of the heartbeat, you overpressure the animal's blood being pumped to the brain,
and cause a blackout. Sometimes as extreme as bursting blood vessels in the animal's brain. Which is
supposed to explain the instances when an animal drops like a bag of rocks, rather than going on
a terminal mad dash for 75 yards. But no caliber will guarantee this, it's just a matter of fortuitous
timing, upon occasion.

 

[brewer12345]

But that's for states where bullets that don't necessarily expand are completely legal.

Its funny. I take pains to stay within the published regs and laws because it is my nature. That said, many of them have little basis in practical experience or any sort of reality. Even worse, for a lot of them I think it would require a ton of resources that the state agency does not have to tell whether you are on the right side of the law. The 1000 ft lb at 100 yards is an example. I took my mulie doe with a 30-06 round where I cast the projectile and loaded the shell. Short of some fairly involved testing, how the heck would a game warden know if I met the standard? Would the roughly 12 BHN lead bullet meet the requirement for "expanding"?

FWIW, the load data I was using indicated that I was comfortably over the energy requirements at 100 yards and terminal performance suggests the bullet (which I did not recover) expanded since the exit hole was half an inch in diameter. That said, I have no actual data derived from testing that says everything was in compliance with the law. I never saw a game warden when I was deer hunting either.

 

[jmorris]

Enough to kill it as quickly as possible.

A truck at 88 FPS has enough energy to kill a deer an won’t even leave a mark on the outside.

I guess that’s one reason I lean towards more than enough weight but I do tend to prefer higher velocity’s.

You can take a Bovine that weighs more than a half ton and drop it like a sack of potatoes with a .22 short, so energy isn’t the only part of the equation either,

 

[Random 8]

I'm assuming the OP is relatively new to hunting deer with a rifle. Apologies if this is incorrect. For this reason I will simplify my response, leaving a lot of the ballistic-ese out. Energy as stated above is a simple number to calculate. Therefore, it is a simple yardstick for comparing cartridge effectiveness on game animals. One can get more complicated, as above, but this is not necessary for the novice. When I started hunting deer, the 1000 ft lb rule was widely touted. It is widely effective. Assuming proper bullet construction, I cannot think of a 1000ft/lb rifle cartridge that will not reliably anchor a deer with decent, not perfect, shot placement. Venerable rounds such as the .30-06, .270 Win and .308 win will carry 1k ft lbs to 300 yards with a spitzer bullet. The old timers, .30-30 win and .35 rem will do it to shorter ranges. These 5 have probably killed more whitetail than Northern winters. Rounds with less muzzle energy will definitely kill deer, and may do it effectively with less than perfect shot placement, but I think the 1000 ft lb "rule" is a good yardstick.

 

[buck460XVR]

While I will not say that bullet energy is a high priority, I also will not say it is worthless. It is a measurement, and altho to most of us, subjective, has been used objectively by wildlife managers because there is not another universal measurement to set minimum standards when marginal weapons may be used. It is a simple measurement, bullet weight X bullet velocity, and many of us could compare random factory ammo by just those two figures. That's because many of us have experienced in the field the damage done by a 180 gr 30-06 bullet going 2800FPS. Not everyone has this experience and those that do, might want to compare it to another caliber/bullet weight. That's what I see it as, a way to compare so one can have realistic expectations of what to expect. While bullet construction, bullet placement and distance to the target are variable and will change in the field, bullet energy will not. For the most part, it is a moot point to those of us that reload our hunting ammo.

 

[Varminterror]

An interesting concept I heard of a while back is that if you hit the animal thru or near the vitals at the "upstroke" of the heartbeat, you overpressure the animal's blood being pumped to the brain, and cause a blackout.

The stuff people will believe.... SMH....

Run this by your cardiologist. It’s nothing but pseudoscience and absolutely untrue.

You’re talking about a hydraulic system running a couple pounds of pressure (120/80mmHg = ~2.3/1.4psi), and running into it with an incredibly high pressure collision. The impact pressure on the closed system is far greater required to overcome any significance of the “beat” pressure. Beat or off beat, the bullet running into the heart would cause far greater effect than the position of the heart valves. Just silly.

 

[MaxP]

The biggest animal I've killed to date I did with a .480 Ruger load that calculated out to just under 1,300 ft-lbs of ME, and it was very decisive. I find minimums for deer dubious. It doesn't take much to kill a deer as they are pretty lightly constructed. I would be more concerned with bullet quality and accuracy. JMHO.

 

[MCgunner]

I still believe the old 1000 ft lbs on target is a good rule of thumb. That don't mean less can't do the job, but if you're choosing a new cartridge, I think that's a good rule of thumb. Yeah I know .22LR has killed deer....head shot no doubt. But, aside from the fact that rimfires are illegal in Texas, I'll stick with centerfires. I HATE losing venison.

And, I KNOW (save your breath bow hunters) that there are other ways to kill a deer. But, with a firearm, the 1000 ft lb rule of thumb is good with me. I really don't care if the rifle does this with mass (385 grain Minie ball) or velocity. In fact, the more velocity dependent the cartridge, the more dependent on good bullet performance it will be. The good news is there's a good variety of excellent controlled expansion bullets now days, but that 385 grain Minie doesn't need any expansion to get the job done.

I have killed one deer with a .223 Barnes 62 grain bullet at 2800 fps. It worked, at 30 yards. It carries almost 1200 ft lbs, after all, at the muzzle. But, my go to round/rifle is my .308. I've been successful with everything from crossbow bolt to muzzle loader to .223 to 7mm Rem Mag to .357 magnum to even shotgun with 3 buck (20 gauge). Choose your poison.

 

[d2wing]

Despite what some on here say, according to actual ballistic engineers energy is a precise measurement that indicated relative destructive power of a bullet. Expanding bullets is where resistance of flesh causes a soft point of sufficient velocity to expand tearing up the flesh. The more energy the wider the wound and the more damage. The key is to destroy a vital organ so the animal will die. If you hit the heart the animal will die regardless of bullet used. If you hit the lungs you need to do enough damage that the deer will die quickly. If you use pistol calibers or slow cartridges, the wounding mechanism depends on hitting a vital part without doing much damage to any surrounding part as the wound channel will depend more on the size of the bullet, it's mass and speed. If you penetrate the heart, the deer will still die. The Lungs, it will still likely die but slower. Head, neck and CNS type shots are iffy and the bullet used is less important. Deer are not very big, they are less that a foot thick usually.
So use whatever is legal in your state and be a good shot. Where you place the bullet is most important. The caliber is not real important. Remember on gun forums you will hear a lot of stuff. Some on claim science is made up by manufacturers or gun writers for reasons that make no sense at all. But opinions make gun boards interesting. Much of our information comes from the military and the International Society of Ballistic Engineers, except what you read on gun boards. Anyone can write a book or post ideas. Ammunition manufacturers sometimes put icons on there boxes to indicate what class of animal the bullet is designed for as in rate of expansion, velocity and mass( energy). Some bullets expand instantly for prairies dogs. slower for deer, slower still for elk. Then there are FMJ bullets not intended for hunting at all and illegal in most places. Solids for African game. And cast lead bullets that work well but are limited in velocity. But do not underestimate the slow heavy bullets. The killed some species into extinction.

 

[CraigC]

Energy is useless. Which is not to say that kinetic energy as a concept is not in play but that the calculated quantity is useless in any discussion of terminal ballistics. Until we can determine exactly 'how' that energy is being used, it has no meaning. We do not know how much is absorbed by the fluids and soft tissues of the body, how much is being used to destroy tissue and break bones, how much is being used to deform the bullet, how much is lost through friction/heat, etc., etc.. Without knowing all that, the total quantity of it is a meaningless number and it doesn't take an engineering degree to figure that out.

I'd love to hear an example of where kinetic energy numbers tell us anything useful. Without knowing any other details, is a cartridge/load producing 2000ft-lbs automatically "better" and more effective than 1000ft-lbs? Better for what, deer, varmints, elephant? Can you answer the question without knowing any other details? If you were to push a .357 carbine into elk duty, which would be better, a 125gr JHP at 2100fps or a 180gr WFN at 1600fps? Do you need energy figures to answer that question? Not if you know anything about terminal ballistics. Does it change anything knowing that the 125gr load produces 1200ft-lbs of energy and the 180gr produces 1000ft-lbs of energy? Those are not dissimilar cartridges but two common loads for the same cartridge. Is energy what makes the 125gr a better varmint load? No. It's the lighter construction and higher velocity, ensuring a flatter trajectory and explosive expansion. You can figure all that out without energy. By the same token, if we push that 180gr 400fps faster and thereby increase its calculated energy by 60%, does that make it 60% more effective? Does it make it more effective at all? No. In fact, it could make it less effective by driving the bullet too fast for the material it's made from. Let's make the bullet a monolithic copper solid, does that make it more effective? Perhaps, a little bit but certainly not 60%. So of what use was kinetic energy in figuring all this out?

Let's compare dissimilar cartridges. Is 4700ft-lbs automatically better than 1200ft-lbs when the game is the size of Cape buffalo, hippo or elephant? Is a .375H&H launching a 270gr expanding bullet at 2800fps more capable than the same weight solid out of a .44Mag at a relatively sedate 1450fps? Does having over four times the energy make it capable of taking game four times larger? The answer is a resounding NO. In fact, the .44 will outpenetrate the .375 and break heavy bones without deforming. So tell me again what role energy plays in this scenario? Many have said that 1000ft-lbs is minimum for deer, what about 1200ft-lbs on 2000lb water buffalo?