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ZeroJunk
January 3, 2007, 09:27 PM
If you shoot an animal with a 150 grain bullet traveling at 3000 FPS and the bullet exits the animal at 2000 FPS, is that more energy transfered than the same bullet traveling at 1000 FPS that stops in the animal?May be a physics equation for this,but I don't know what it is.

buckeye718
January 3, 2007, 09:42 PM
Let me be the first to say,where in the world did you come up with that question? I hope there is someone with a degree on here,because now you've got me consered. LOL I want to here the answer.

fisherman66
January 3, 2007, 10:09 PM
If you shoot an animal with a 150 grain bullet traveling at 3000 FPS and the bullet exits the animal at 2000 FPS, is that more energy transfered than the same bullet traveling at 1000 FPS that stops in the animal?May be a physics equation for this,but I don't know what it is.

Are you assuming the entire 150 grains exited? That's not likely to happen in the real world with modern hunting bullets.

The stretch cavity would also be much different in your second example.

Below is a link to an explanation of how speed and mass work. You could also google "corded bat" and get a practical example.

http://en.wikipedia.org/wiki/Mass

mete
January 3, 2007, 11:06 PM
Energy never killed anything !! You must penetrate into the vital organs and do damage to them !!!

Scorch
January 4, 2007, 12:30 AM
If you shoot an animal with a 150 grain bullet traveling at 3000 FPS and the bullet exits the animal at 2000 FPS, is that more energy transfered than the same bullet traveling at 1000 FPS that stops in the animal?

Yes, because energy quadruples as the velocity doubles, and you are losing 1/3 of the velocity, so roughly about 60% of the energy is delivered to the animal in the form of hydraulic shock that created the wound channel.

A 150 gr bullet traveling at 1000 fps would have roughly 350 ft/lbs of energy, not much for taking on a game animal.

The same 150 gr bullet at 3000 fps would have approximately 2900 ft/lbs of energy, and at 2000 fps it would have about 1300 ft/lbs. The energy delivered to the animal's tissues is the difference, about 1600 ft/lbs.

JohnKSa
January 4, 2007, 12:59 AM
Scorch is right.

Assuming there's no loss of projectile weight.

The bullet which entered at 3000fps and exited at 2000fps expended approximately 1665ft/lbs of kinetic energy in the animal.

The bullet which entered at 1000fps and did not exit expended approximately 333ft/lbs of kinetic energy in the animal.

mete is sort of right & sort of wrong.

1665 ft/lbs is not enough energy to kill if the vitals are not hit.

Kinetic energy is the scientific measure of a projectile's potential to do damage. Therefore, any thing that is killed by a projectile is killed by energy. Projectiles without energy are harmless unless you step on one and it hurts your foot. ;)

ZeroJunk
January 4, 2007, 07:19 AM
Thanks.I guess it should have been intuitive.I'm trying to get my mind around this never ending discussion about caliber and velocity.

Fat White Boy
January 4, 2007, 11:48 AM
If the bullet isn't placed properly- Caliber, Velocity and Energy are irrelevant...

ZeroJunk
January 4, 2007, 12:21 PM
FWB,I don't think anybody would argue that point.But game animals have a tendency to get themselves in a position where it is very inconvenient to get a good rest.I don't know that anybody intentionally takes a marginal shot but sometimes they turn out that way.A marginal shot with a higher energy bullet will more likely get you meat in the freezer.My interest pertains to some failures I have had with some really fast bullets zipping through both lungs of a deer and causing little damage and obviously retaining most of their energy after passing through.I have shot a bunch of deer and I know if the bullet had been a 1/2 inch either way and hit a rib on entry it would have slammed the animal on the spot,instead of me having to track him 200 yards.Perhaps a smaller bullet would have expanded in the soft tissue anyway.Perhaps a larger caliber with a larger surface area would have worked better.The notion that everyone is always going to make heart shots is unreallistic.There is no simple conclusion to this.

lizziedog1
January 4, 2007, 12:31 PM
Bullet energy is another over used and over hyped term. Energy alone doesn't kill. If energy was such a factor, the original .45-70 loads would be next to useless for big game. The Bison shouldn't have been wiped out.

mikejonestkd
January 4, 2007, 12:33 PM
Zero,

I actually have a degree in engineering and it is more complicated than just comparing the impact velocity vs the exit velocity.

There are way too many variables in hunting and no two shots are the same.
If you are using a fairly high velocity rifle and not getting the energy transfer that you seek, may I suggest a more fast opening bullet? Perhaps a NBT, sierra game king, accutip or something similar. IMO you do not need a partition, bonded, failsafe, or any fairly tough controlld expansion bullet for broadside shots at deer.

just my .02 cents take is for what its worth.

I believe if I recall correctly in Jack O'conner's Complete book of rifles and shotguns he referenced Cap. Crossman who felt that a .25 caliber 100 gr fast opening bullet travelling at 3000 fps was IDEAL for deer sized game.