Bullet lethality: energy and velocity

[MTbackwoods]

Every hunting bullet has it's minimum impact velocity for expansion as per the manufacturer, it's usually around 1850 fps.

The muzzle velocity is not the correct velocity to use to determine suitablility of a bullet.

The velocity of the bullet at the distance you are hunting is the right velocity to use.

There are calculators that can give you how fast a bullet is still travelling when it is a certain distance from the muzzle.

Calculate how far the bullet is from the muzzle when it is at the minimum velocity for expansion, and you have your practical hunting range limit.

Correct. But my 7mm loaded with 162 ELD Ms carries necessary velocity out to 1350 yards. But let's just say that 1,000 ft/lbs was the accepted limit for good lethality. I would then have to dial my maximum range back nearly another 100 yards to 1,250. So that's what I'm asking for information on. Assuming velocity is within manufacturers recommendations, where does a lack of energy become a big enough concern to dial back on maximum effective range?

 

[338 dude]

I have a .338 RUM as well that I'm launching the 285 ELD M at 2,900 FPS. It's more than adequate, as I think we can all agree. However, I love my 7mm. So I'll give yet another example. My ballistic calculator says that my 338 hits the velocity threshold of 1,600 FPS at 1,575 yards and the bullet still has 1,626 ft/lbs of energy. We can all agree that that is plenty of energy to be quite lethal. Now let's switch to the Nosler ABLR. If I put the 265 ABLR at a starting velocity of 2,950 FPS, which I think is a fair increase due to less weight, and trust Nosler's claim that the bullet will expand down to 1,300 FPS, I could then reliably kill at 1,850 yards where the bullet only has 984 ft/lbs of energy... if velocity is all that matters (along with bullet design) then I should be off to the races right? Both would then be equally lethal right? If energy doesn't matter then both would have the exact same effect, right?

As Feenix said you must consider the target nearly 1000 foot pounds on a deer is fine but an elk would require more and I agree with what was said about 1500 pounds for an elk or moose size animal

 

[338 dude]

Just for sake of argument in this exercise in futility. Does the VLD really dump 2,000 foot lbs? If the VLD comes apart into smaller pieces or shrapnel can it still dump the energy as smaller projectiles versus the accubond continuing on as one solid mass. I would think mass of the object would figure in. We need a physics guru on this one.

I'm not a physics guru at all but I would think the projectile running at the same speed and the same weight the one that fragmented and stopped in the target would definitely dump more energy than the one that passed through obviously energy is wasted as it continues beyond the target

 

[KurtB]

I see 140 Berger vld bullets expanding reliably from a low of around 2100 fps to 2900 fps. At those velocities they have penetrated well and caused large amounts of damage to vitals. Probably good down to around 1900 fps but that is a guess. I'd shoot elk on down as long as my impact velocity allows expansion. I don't care about energy, just tissue damage.

 

[338 dude]

I see 140 Berger vld bullets expanding reliably from a low of around 2100 fps to 2900 fps. At those velocities they have penetrated well and caused large amounts of damage to vitals. Probably good down to around 1900 fps but that is a guess. I'd shoot elk on down as long as my impact velocity allows expansion. I don't care about energy, just tissue damage.

To put it as simply as I can explain it is all about balance

 

[FEENIX]

Just for sake of argument in this exercise in futility. Does the VLD really dump 2,000 foot lbs? If the VLD comes apart into smaller pieces or shrapnel can it still dump the energy as smaller projectiles versus the accubond continuing on as one solid mass. I would think mass of the object would figure in. We need a physics guru on this one.

I too am no physics guru but if a VLD bullet fragments and implodes internally as designed, the animal absorbed all of the energy. On the other hand, a solid mass of accubond that passed through has wasted energy that the animal did not absorb on impact.

 

[Canhunter35]

Destruction of vital tissue is what matters.

I know of (first hand) of a man killed instantly by a .22LR fired from so far away witnesses, and shooter were unaware of the others presence.

Both humans and animals, can be very "fragile" one moment, then appear "indestructible" in another.

We're currently living in an absurd majority rules situation.

Thought this too good to not share again

 

[Canhunter35]

I agree! There are many lethality/knock down power index out there but they are simply a guide. "My" unwritten rule is 1500 FT-LBS for elk and 1000 FT-LBS for deer at point of impact and within the min velocity of the bullet to expand accordingly. The "NUT" behind the trigger remains the key factor in lethality.

I've shot deer below 1000ft lbs of energy...that's a good limit, I would recommend staying above it too

 

[JASmith]

There is ample evidence to suggest that, absent a hit to the central nervous system o major support bone, the key factor in bringing down an animal quickly is the time it takes for cranial blood pressure to drop. In this regard, bullets act in the same manner as have arrows for millennia.

In the thorax, that means cutting arteries and veins. The more cut, the faster the pressure drop, with ten seconds being fast enough to keep the animal from running more than about 100 meters. At some point, more cut arteries and veins does not cause fainting much sooner so we get a balance between hole size (broadhead width or expanded bullet diameter and their respective weights) and how far the animal runs on average.

That balance then translates into the size of arrow and bullet characteristics.

 

[FEENIX]

I've shot deer below 1000ft lbs of energy...that's a good limit, I would recommend staying above it too

Me too, but as you noted, I prefer to keep it above the threshold.

 

[HARPERC]

When there is enough energy to launch a rock chuck doesn't seem to matter where they're hit, I suspect the same thing works for elk.

"Splash" a bullet on a shoulder, you've got energy, and problems. "Dump" energy on a rear raking shot, your day just got longer.

A question I've always had, but not educated enough to answer. How much of our "energy" is used to change bullet form?

Velocity, and energy can't really be separated. If it moves it has velocity and energy. If it doesn't move it will take energy to get it started.

Anatomy and physiology are higher on my list. When I work with beginners we use a lot of picture targets. Fire a shot, walk to the target, and discuss the probable outcomes of the placement..

 

[Wingmaster 20]

I don't think you have a valid question with the answer you are looking for.

Bullet velocity creates the expansion of given bullet.

Energy is a factor of the specific bullet at that velocity.

Sectional density would also come into play as frontal area will also have an effect

So the answer to your question has far to many variables to provide an answer.

The simple answer would be, a bullet that is traveling fast enough to initiate expansion while providing enough penetration to cause enough blood loss to kill the animal.

That is my opinion.

Steve

At some point you have to stop asking questions and shoot. The question that is more important in this forum is: Can I get closer to the animal before I shoot?

 

[AlphaDogs]

WM20 be aware you are treading close to a sacred topic.

 

[MTbackwoods]

At some point you have to stop asking questions and shoot. The question that is more important in this forum is: Can I get closer to the animal before I shoot?

Agreed. But that's always option #1 for me. But the reason I gained interest in long range shooting and hunting is because I found myself in too many instances where getting closer was not at all possible. I've had to watch 3 6x6 bulls walk away from me at an estimated 600 yards because I didn't have the equipment or skills to pull of that kind of shot. I decided I wasn't going to let that happen any more