FPE foot pounds of energy

[fredoesway]

so does anyone else wonder about foot pounds of energy, FPE. it doesen't make sense to me. cant we come up with a better formula for this. game animals are not made of steel. despite what the magnum lovers say. something along the line of bullet weight bullet construction and pentration value or some other formula. after all FPE is an ancient formula. what 100 years ago or more. seems that bullet makers could calculate pentration value or some other formula.

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[bbbass]

so does anyone else wonder about foot pounds of energy, FPE. it doesen't make sense to me. cant we come up with a better formula for this. game animals are not made of steel. despite what the magnum lovers say. something along the line of bullet weight bullet construction and pentration value or some other formula. after all FPE is an ancient formula. what 100 years ago or more. seems that bullet makers could calculate pentration value or some other formula.

Use any yardstick/metric you like, what happens in the field on any particular day with any particular animal has enough variables to frustrate even Bobby Fisher.

 

[EHJ]

Newton Meters and Joules!

 

[fredoesway]

yes and Taylors KO value

 

[EHJ]

yes and Taylors KO value

Today I learned a new thing...!

Thanks!

 

[Lennie]

Foot lbs. of energy is not the best guide for round selection.

That said, even among experts, there is disagreement as to what offers the best information for bullet and caliber selection.

Yes, I agree with fredoesway, Taylors KO value is a good source for judging a rounds potential.

Another good formula is Hornady's HITS formula. I also like to look at the this formula.
(Bullet weight)^2*(Bullet velocity)/(700000*Bullet diameter^2)

Here is a discussion on it
http://poncarpc.org/rifle ballistics-part v.pdf

 

[thorborg]

so does anyone else wonder about foot pounds of energy, FPE. it doesen't make sense to me. cant we come up with a better formula for this. game animals are not made of steel. despite what the magnum lovers say. something along the line of bullet weight bullet construction and pentration value or some other formula. after all FPE is an ancient formula. what 100 years ago or more. seems that bullet makers could calculate pentration value or some other formula.

Understanding FPE is no mystery if you understand basic math and mechanics. None the less, I never really worried about it.
For me it was time and materials. Time spent hunting, then examining the effects of the materials used. You ask an awful lot when the variables for not just ballistics, but game conditions, are infinite in combination. Because of modern projectile development, FPE's contribution towards expected outcome has taken a lessor active role. (though still impressively important)
If FPE is important, or even just a wonderment, just go by what is offered by the major ammo producers, for the game you intend to hunt, and you will be successful when doing your part.
One word of advice, autopsy every kill, along with reflection on the situation making it happen, and things like FPE will eventually become moot.

 

[Koda]

Actually Chuck Hawks has a "Killing Power Score" formula that I think is pretty close to practical. The problem with any formula though is its subjective to what "score" it yields that will work for your target...


Energy at 100 yards (in foot pounds) x Sectional Density (taken from reloading manuals) x cross-sectional Area (in square inches) = Killing Power Score at 100 yards.

• E x SD x A = KPS

Rifle Cartridge Killing Power Comparison

 

[fredoesway]

Foot lbs. of energy is not the best guide for round selection.

That said, even among experts, there is disagreement as to what offers the best information for bullet and caliber selection.

Yes, I agree with fredoesway, Taylors KO value is a good source for judging a rounds potential.

Another good formula is Hornady's HITS formula. I also like to look at the this formula.
(Bullet weight)^2*(Bullet velocity)/(700000*Bullet diameter^2)

Here is a discussion on it
http://poncarpc.org/rifle ballistics-part v.pdf

interesting link

 

[pharmseller]

The following is my opinion, based on experience.

Energy is stupid. Knockdown power is a myth.

Velocity is key. Determine your maximum distance then select a cartridge that provides sufficient velocity for your chosen bullet's performance window. That's usually 1800 feet per second (fps).

Quality bullet at proper velocity.

Then go buy a stainless Tikka in 7mm-08.

 

[belshawelk]

I will disagree with everyone.. energy is what kills. Velocity is what delivers it. Having the right bullet at the right energy delivered at the right speed kills.

Anyone remember why the 10mm came out. the 9mm have lots of velocity, just not enough energy. Heavy bullets moving faster create more energy. energy puts a body in shock then kills. I don't take chances in hunting on a perfect bullet placement every time. I seen that game played of lots of times.

 

[RVTECH]

something along the line of bullet weight bullet construction and pentration value

BWBCAPV - too many letter! FPE is much shorter.

 

[Koda]

energy puts a body in shock then kills. I don't take chances in hunting on a perfect bullet placement every time.

I havent seen any evidence that shock is what kills. Im not certain what you mean by not taking changes with shot placement? Shot placement is probably the most crucial part of this subject regardless of where one stands on the energy vs velocity debate.

 

[Andy54Hawken]

Speaking only for myself in regards to FPE , KO and etc...tables..

Animals don't read such tables.....

Bullets can do weird things when they hit flesh...

Choose a rifle in a caliber and use a bullet style that , is appropriate to the game which you wish to hunt...

Practice with that rifle , caliber , bullet style...
And by practice , I mean often , and not just under shooting range / bench conditions.
Go out and practice under hunting conditions , in poor light , after carrying the rifle all day , in the rain , etc...

Find out at what distance you can make good hits with , and stick with that...

Learn that hunting is different than shooting...

One of the many reasons that older "tried and true" rifles , calibers and bullet styes exist...
Is 'cause they still work and work well..
No matter what a table or a gun writer has to say 'bout 'em.
Andy

 

[pharmseller]

I will disagree with everyone.. energy is what kills. Velocity is what delivers it. Having the right bullet at the right energy delivered at the right speed kills.

Anyone remember why the 10mm came out. the 9mm have lots of velocity, just not enough energy. Heavy bullets moving faster create more energy. energy puts a body in shock then kills. I don't take chances in hunting on a perfect bullet placement every time. I seen that game played of lots of times.

So energy is dependent on velocity? Put another way, without sufficient velocity there's insufficient energy? Or, energy depends on velocity?

 

[belshawelk]

So energy is dependent on velocity? Put another way, without sufficient velocity there's insufficient energy? Or, energy depends on velocity?

Well lets put it this way. Do you want to get ran over by a bicyclist at 40 MPH or a mack truck doing the same. How about a train moving 30.What do you think it going to work out best for you.

Or do you want to get shot with a .22 at 1500 PFS/ at point blank at 150PFE. Or get hit by a 300WM at same velocity at 1,000 yards with 500FPE

Velocity is USELESS without energy. Go drop a nail and a hammer from you waist on your foot. Both with hit at the exact same time. Same velocty See what hurts more. Heck even throw the nail so its going faster.

 

[Koda]

Hunting is an interesting subject because its one of the only life disciplines that has virtually no instruction manual, it can only be learned heuristically or from a mentor. Not even the various fish and game departments across the country have a consensus on what kills best. I recently learned in Montana any centerfire rifle cartridge is legal for elk.... so that includes the .223. Other states go exclusively by energy only which causes confusion.
There are just too many variables that need to come together, to just rely on energy sets up failure. Personally, one of the more overlooked components in this subject is sectional density, if I had to debate just one component of the killing power, id put sectional density over energy.

Luckily, there is over 100 years of heuristically collected data documented in hunting lore thanks to the web. If one really wants to understand a given cartridge killing power there are a few really good articles written by Chuck Hawks on his web blog. He has several good articles on the subject but this bookmark is one thats a great summary to start with...

KILLING POWER

 

[belshawelk]

I havent seen any evidence that shock is what kills. Im not certain what you mean by not taking changes with shot placement? Shot placement is probably the most crucial part of this subject regardless of where one stands on the energy vs velocity debate.

Yes shot placement is important. But all the snipers out there think its easy to shoot an elk. When you do miss the sweet spot and it will happen because wind, movement, elevation, brush or whatever. While I am not some long range sniper, I can hold my own. I no longer shoot for vitals on elk. I have been involved with elk running a really long ways and sometimes never found until it's too late with a lung, heart or liver shot. They do not run anywhere with broken shoulders or one broken shoulder and a vital hit. If you have ever hunted big bears the first thing you want to do it break it down. That is energy.

 

[TTSX]

Can we all just agree that if it doesn't start with a 4 and end in a 5, Jesus didn't make it

 

[SCARed]

Well lets put it this way. Do you want to get ran over by a bicyclist at 40 MPH or a mack truck doing the same. How about a train moving 30.What do you think it going to work out best for you.

Or do you want to get shot with a .22 at 1500 PFS/ at point blank at 150PFE. Or get hit by a 300WM at same velocity at 1,000 yards with 500FPE

Velocity is USELESS without energy. Go drop a nail and a hammer from you waist on your foot. Both with hit at the exact same time. Same velocty See what hurts more. Heck even throw the nail so its going faster.

You're correct but using the wrong part of the math equation. Mass is what you're talking about.

Mass*Velocity = Energy