Foot Pounds energy (fpe)
Mar 13, 2011 13:13:36 GMT -5
Post by wilmsmeyer on Mar 13, 2011 13:13:36 GMT -5
There has been a few discussions here regarding FPE and how much is needed to kill this or that humanely. Some think fpe is also a measure of lethality and killing power.
Although FPE is a number that is calculated relatively easily, it is simply a number.
To say that a lethally stuck or struck animal that was only hit by X amount of FPE will die quicker then Y amount of FPE is foolish if talking FPE only.
Many things contribute to the rapid "knockdown" of an animal.
1) vital organs disabled - time runs out quickly but animals can cover ground during this time. For instance: A perfect top of the heart double lung pass through of ANY animal. A 425 grain arrow at 275 fps has roughly 70 FPE. This is considered a very humane and awesome killing combo that will work on big game by any bowhunter. A .22 short, 29 gr bullet at 1,000 fps has about the same energy. However, even the most carefully placed .22 short, behind the shoulder of a big game animal would be extremely in-efficient.
2) Bone and structure disabled - Certain areas that can be disabled and put animals down are the spine and shoulder bones. Even the hips, although this isn't a target area. In this case, only a lucky arrow with 70 FPE will get to these spots. But a bullet with adequate FPE can...and not a 22 short.
3) Speed, accompanied by penetration, will cause some hydraulic disruption of blood vessels and the nervous system and cause an animal to expire quicker.
So, FPE is a number that although able to be calculated, does not represent lethality in any way.
I have killed several...as in over 100 deer....with very powerful loads from a savage ML. A few also with big shotgun slugs and a few with CF rifles using proper ammo. Let's take one load in particular. 250 TMZ at 2800 fps. Muzzle energy about 4,350. Wow...That's 60 TIMES the amount of the arrow mentioned above. I have blown a golf ball size hole through the top of the heart and both lungs of average sized deer at 25 yds with this load. Neither hydraulic shock, massive FPE or any other magic have made these deer fold like a house of cards. Most simply run 50-75...or 100 yds as they bleed out. Many have run farther with the same hit than deer I have punctured with an arrow in the same place
The rare exceptions of DRT results have been when the shoulder and/or spine gets in the way...at any distance.
There is a certain need for a specific amount of FPE required to drive a bullet/projectile into the vitals...or break bones and continue to penetrate. This amount is completely contingent on the projectile being used. Its weight, diameter and construction corralate here. For instance, a .243 shooting a 55 grain varmint bullet at 4,000 fps has roughly 2,000 fpe. That's alot....but the bullet is too lightly constructed to utilize that big number when all you consider is "the number". As mentioned earlier, 70 FPE will cut a big hole all the way through with an arrow/broadhead on even an elk or moose. There is no intent to drop the animal in its tracks....just to ensure a humane death.
Let's take a .44 mag with a 250 gr hard cast bullet. These bullets are notorious for extreme penetration on the biggest game. With a MV of 1,400 fps, the max FPE to be had is at the muzzle....1085 FPE. Rarely are animals shot point blank range so it is safe to assume that under 1,000 FPE...with this combination...will get the job done.
Anyone using the FPE number as a standard rule of thumb needs to analyze what they are talking about and understand some principles of how things work. Saying you need at least "X" FPE to kill a deer or elk must be quantified by many things such as the bullet, caliber and construction.
What did everyone use at several hundred yards to basically wipe out the bison population in the 1800's? how much FPE were they working with?
A 45-70 using a 405 grain bullet would be a great elk gun as far as the shooter could place a shot...let's say 150 yds? What is the FPE?......Assuming 1,400 fps at the muzzle and 1100 fps at 150 yds...FPE is just over 1,000 lbs.
Be careful in using numbers when talking FPE. Try understanding that number...understanding ballistics and understanding what makes a shot a killing shot.
Although FPE is a number that is calculated relatively easily, it is simply a number.
To say that a lethally stuck or struck animal that was only hit by X amount of FPE will die quicker then Y amount of FPE is foolish if talking FPE only.
Many things contribute to the rapid "knockdown" of an animal.
1) vital organs disabled - time runs out quickly but animals can cover ground during this time. For instance: A perfect top of the heart double lung pass through of ANY animal. A 425 grain arrow at 275 fps has roughly 70 FPE. This is considered a very humane and awesome killing combo that will work on big game by any bowhunter. A .22 short, 29 gr bullet at 1,000 fps has about the same energy. However, even the most carefully placed .22 short, behind the shoulder of a big game animal would be extremely in-efficient.
2) Bone and structure disabled - Certain areas that can be disabled and put animals down are the spine and shoulder bones. Even the hips, although this isn't a target area. In this case, only a lucky arrow with 70 FPE will get to these spots. But a bullet with adequate FPE can...and not a 22 short.
3) Speed, accompanied by penetration, will cause some hydraulic disruption of blood vessels and the nervous system and cause an animal to expire quicker.
So, FPE is a number that although able to be calculated, does not represent lethality in any way.
I have killed several...as in over 100 deer....with very powerful loads from a savage ML. A few also with big shotgun slugs and a few with CF rifles using proper ammo. Let's take one load in particular. 250 TMZ at 2800 fps. Muzzle energy about 4,350. Wow...That's 60 TIMES the amount of the arrow mentioned above. I have blown a golf ball size hole through the top of the heart and both lungs of average sized deer at 25 yds with this load. Neither hydraulic shock, massive FPE or any other magic have made these deer fold like a house of cards. Most simply run 50-75...or 100 yds as they bleed out. Many have run farther with the same hit than deer I have punctured with an arrow in the same place
The rare exceptions of DRT results have been when the shoulder and/or spine gets in the way...at any distance.
There is a certain need for a specific amount of FPE required to drive a bullet/projectile into the vitals...or break bones and continue to penetrate. This amount is completely contingent on the projectile being used. Its weight, diameter and construction corralate here. For instance, a .243 shooting a 55 grain varmint bullet at 4,000 fps has roughly 2,000 fpe. That's alot....but the bullet is too lightly constructed to utilize that big number when all you consider is "the number". As mentioned earlier, 70 FPE will cut a big hole all the way through with an arrow/broadhead on even an elk or moose. There is no intent to drop the animal in its tracks....just to ensure a humane death.
Let's take a .44 mag with a 250 gr hard cast bullet. These bullets are notorious for extreme penetration on the biggest game. With a MV of 1,400 fps, the max FPE to be had is at the muzzle....1085 FPE. Rarely are animals shot point blank range so it is safe to assume that under 1,000 FPE...with this combination...will get the job done.
Anyone using the FPE number as a standard rule of thumb needs to analyze what they are talking about and understand some principles of how things work. Saying you need at least "X" FPE to kill a deer or elk must be quantified by many things such as the bullet, caliber and construction.
What did everyone use at several hundred yards to basically wipe out the bison population in the 1800's? how much FPE were they working with?
A 45-70 using a 405 grain bullet would be a great elk gun as far as the shooter could place a shot...let's say 150 yds? What is the FPE?......Assuming 1,400 fps at the muzzle and 1100 fps at 150 yds...FPE is just over 1,000 lbs.
Be careful in using numbers when talking FPE. Try understanding that number...understanding ballistics and understanding what makes a shot a killing shot.
