I just finished reading another thread and in it some author had decided it took 2000# of energy to kill an elk at 200 yards. And over the years, I have read various engery numbers needed to kill deer, goats, sheep, etc. These numbers often seem to be very arbitrary and kinda unique to the writer. How are these figures arrived at?

Mostly some magazine writer makes a statement about it even if it's not based on fact as much as his opinion. People then read it, pass it along and pretty soon people take it as fact.

They may also be extrapolations for military terminal ballistic studies done on animal carcasses.

In any case, I can't imagine that they'd be able to take into account the incredible strength shown by some animals when struck.

They are just some gunwriters personal observations and beliefs put into print. They do not mean too much. I have killed many deer with handguns developing half the 1000# minimum quoted for deer. I guess I am guilty of breaking the law of physics.

I don't know. Now that I've gotten that out of the way, I'll take a stab at it. We all enjoy talking about how one cartridge is better than another for a given purpose (because we all know whatever we carry is obviously the best). But for years, hunters have generally known what it takes to cleanly take certain game animals. Any cartridge has a history of success with certain game animals. With all the ballistic calculators available today, it's not difficult to determine the remaining energy at point of impact. From there, it's pretty easy to say what's been working successfully. If most elk cartridges have around 2000 pounds at impact, that must be about right? At least, that's what we've been saying for years.

Bullets are better now than they've ever been. Today's controlled expansion bullets behave as if they had a much higher sectional density than they actually do. Many still use heavy-for-caliber bullets, but better constructed bullets can be of lighter weight, driven faster, expand reliably, and still penetrate. Sectional density still counts for adequate penetration when conventional bullets are used, but the need for that is changing every day.

Some animals could obviously care less about foot pounds of energy. It still takes heavy bullets making big holes to bring down the largest game. Any more, remaining energy must be taken with a grain of salt. A 55gr .22 caliber excelerator fired from a 30-06 has over 2000 foot pounds of energy, just like the .375 Winchester firing 250gr bullets. Does that make the .22 an elk cartridge? Hardly. Foot pounds of energy is actually a strange way to qualify terminal ability. Linear measurement of energy would be a little more applicable, but the foot pounds measurement we still use is still somewhat useful for comparing apples to apples.

In Ackleys book there is that data for different animals under the chapter "Killing Power". For deer, antelope, sheep and goats the minimum is 900 ft/lb, adequate 1200 ft/lb and preffered 1500 ft/lb. This is the remaining energy at the game.

The chapter explains how to use the data and makes the point that it is a viable guide.

Of course there are variables but it's discussing rifle bullets at various ranges and game.

I think it's a reasonable way to discuss things. It's not the be all end all of information but it is energy that does work.

I think the ft/lbs indices tossed around so frequently are BS. Shot placement is number one, wound channel #2. Terminal Ballistics is as much black art as science because of the multitude of variables involved. It takes a good hold and a good bullet for the task at hand.

It comes from ignorance, from knowing and looking at things only in a linear context, and from people who so badly want to believe in one set of numbers to define everything there is to know about a cartridge.

Savage 99,

In the same book Ackley also states that he believed that the 220 Swift was the best deer cartridge ever made. ( I agree it does a good job) However that negates the " foot pound " arguements. I am sure you were just answering a question with a point of reference instead of making a point yourself. I know you are pretty knowledgable by reading a lot of your other posts.

As far as foot pounds needed. I am glad my bullets don't read these articles about foot pounds, and instead just go out and do their jobs. The jobs that according to most " experts" that they are not capable of doing.

As the needed footpounds being high, sells newer caliber rifles, and the need for more powder to drive the {premium} bullet you now need, that is the basis of footpounds.

I suppose it comes from simply paying attention to what has worked best on which game in the past.

Figuring out how much energy was used is the easy part.

I think I'll have to go with Wstrnhunter on this one. Most of these numbers (Taylor KO etc.) seem to have been developed by people with considerable experience killing things. If you read closely most of them point out that they are ideal numbers that cover a particular species of game at what most of us would consider normal ranges. It is pretty simple to then come up with some general rules about suitable cartridges.

Will a .222 or .223 kill a deer? Of course it will, with excellent shot placement, the right bullet loaded, moon in the right phase etc. Is it a suitable deer round? That's when you get into disagreements, my view is absolutely not for the average hunter. Most people (me included) don't have the patience to wait for the right shot, or the skill to pull it off in the field. Sitting at range with the sling holding me together I can get most of my rifles shooting around 1". In the field, after a stalk, when it's cold, been three hours since breakfast, I'm not sure if I can do that every time or not.

You can argue all you want about shot placement being the key, but a small bullet (for the game) has to be placed exactly right and a more suitable bullet has to be placed about right to get the job done. Think of this scenario, 8 pointer quartering toward you at 125 yards, he's seen something and you don't think he's coming any closer. Do you want to shoot through that shoulder with a 222 or a 270/308/you name it? If you're shooting a 222 or similar it better be a pass, if you're shooting a suitable deer cartridge it's venison in the freezer.

Now you guys that are expert shots, with a great deal of patience don't need to start bashing. I'm not talking to you, it's the rest of the hunters shooting at medium game with cartridges more suited to groundhogs I'm talking to.

Here are some comments on kinetic energy by Harald www.mindspring.com/~ulfhere/ballistics/myths.html#threshold

beeman, you are absolutely correct! The idea that you can specify the number of foot-pounds it takes to kill a particular kind of animal without taking bullet characteristics or bullet placement into account is pure B.S. of the worst sort!

Now, if it takes 2000ft/lb to kill an elk, which may weigh 700-1000 pounds, what does it take to kill an elephant that weighs 15,000 pounds? 15 X 2000?? That would be 30,000 foot-pounds, or 3X the M.E. of the .50 BMG cartridge! In my opinion, ft/lb is a number that is somewhat useful in comparing the power levels of various cartridges, but is totally meaningless as a measure of killing power.

quote:

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Some animals could obviously care less about foot pounds of energy.

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SOME?? I haven't met an animal yet that wasn't carrying a rifle that gave one hoot in hell about foot-pounds!

If you'll note in Ackely's book, it isn't Ackley who listed those ft/lb requirements, it was a fellow named Paul Rosenberg. It seems to me Ackley's own opinions were a little different than Rosenberg's. For instance, Ackley's description of the performance of the .220 Swift on wild burros!!

[ 11-18-2003, 16:31: Message edited by: eldeguello ]

Many of these numbers are simply rules of thumb that have little meaning in the field. A better measure is a line on a graph showing the energy necessary for a 1 shot kill as a function of distance from the center of the vital area. Once you get to big game, the energy number also needs to reflect penetration.

Aside from that the best index I have seen gives a value of 100 to a 375 H&H 300 gr bullet at muzzle and is based on the square of bullet weight times velocity divided by bullet diameter.

Ho hummmmm, these guys have just run out of stuff to write about, its a tough job, they gotta come up with something now and then that hasn't been said more than a dozen times to qualify as an outdoor scribe!