Energy or bullet diameter most important?

[Petey308]

I don't disagree with what Steve said in terms of goals etc… however energy actually has a lot to do with terminal performance. It is nothing more or less than potential to do work. The more energy a bullet has, the more potential it has to do damage. For ex, in the energy link above, what is the difference between a 400 ft-lbs George Foreman punch and a 30 ft-lbs Obama punch. Energy! All of the things talked about causing a longer/wider wound or bubble or whatever is nothing more or less than the result of energy. The more you have the bigger these will be if bullet doing its job

What kills is energy lost (work) by the bullet crushing and tearing tissue by means of temporary and permanent wound cavity. Velocity, bullet construction, cross sectional area, target resistance all affect how the energy is transferred. The reason velocity is important is 2 fold - #1 dynamic pressure, #2 drag. The faster a bullet hits the more dynamic pressure. If dynamic pressure is higher than the material strength of what bullet is made of, the bullet will deform. Once bullet slows down, dynamic pressure reduces and bullet will stop deforming. So higher velocity means more/faster expansion or fragmentation.

The other thing velocity impacts is drag. Drag is proportional to v^2. The diameter of temporary wound cavity (bubble or whatever you want to call it) at any time is proportional to energy transfered at that time . Drag is what influences the rate of energy transfer. Drag is also proportional to the cross sectional area so a wider bullet does similar as higher velocity. Temporary cavity may add to permanent wound cavity based on a lot of things but in general it does in high velocity/energy rifle rounds and not in low velocity/energy handgun rounds

However velocity means nothing without energy and vice versa. It is all intertwined. The reality is so long as you get some decent holes through the vitals bigger holes dont really matter.

Lou

Agreed, and to add: The energy goes to work by converting to force. Not all bullets turn their energy into force, or at least not a lot of force. Some are much better than others and need less energy to begin with. How they convert energy to force is highly dependent upon their construction and the mechanics of how they behave terminally.

This is where the terms energy dump and energy transfer come in. As a bullet converts its energy into force, it rapidly loses momentum. If the bullet loses all its momentum from producing a huge amount of force, it typically doesn't exit. Typically, the higher the rate of momentum lost, the more force is produced and more wounding occurs. That said, you still want to balance it all out so that it occurs within the chest cavity and does the most damage to the vitals. You don't want the bullet to lose all its momentum on or near the surface, for example.

Also, the more momentum the bullet still has, the more force it's still producing. If it produces a ton of force, but simply doesn't lose it all at a rate higher than the speed its traveling, it'll still exit, which we see still with certain soft constructed lead core bullets in certain scenarios.

Ultimately, knowing how the particular bullet you're wanting to use coverts energy into force is what you should focus on and will be much more helpful than going with just a basic rule of thumb on minimum energy. There are many bullets out there that will produce excellent wounding with well under 1000ft-lbs of energy. That's because they're highly efficient at converting energy into force. Conversely, there are many bullets out there that are not efficient at converting energy into force or don't convert very much of it into force.

Frangible bullets are very efficient and effective at converting energy into force. Getting that proper balance though is crucial, and achieved by having sufficient starting mass and not placing the shot in an area where the amount of impact resistance is too much for the impact velocity. But adequate amount of mass at the start can really help with that, as does adjust shot placement for close range shots. A well-constructed and properly selected frangible mono can be very effective as well, to be fair.

 

[RockyMtnMT]

Force is kind of a new term brought into terminal performance discussion. Sounds good though. Force causes a body to move, change direction, or change speed. So there is force from a bullet imparted on what it hits and there is force from the target imparted on the bullet. The energy from a bullet is relatively small but highly focused allowing it to force a small portion of the target to move. The target also contains force. The force to change the speed and direction the bullet is moving. The bullets ability to overcome the force to change direction and velocity imparted on it by the target seems to me to be more important when it comes to predictable repeatable terminal performance. Highly frangible bullets have little ability to overcome the force imparted by the animal. This is the reason they fall short on larger harder targets. This is the reason they have a narrower window of velocity they will function well in. Particularly higher velocity impacts, because the force imparted on the bullet is increased increasing the potential to destruct or fail. Force is the reason that hunters using highly frangible bullets must be careful about shot placement, because they often can't overcome the increased force from heavy muscle and bone impacts. When these shots where high amounts of force causes frangible bullets to fail is when those who advocate the user of frangible bullets will explain that it was not a failure of the bullet but shooter error. The shooter should have known the limitations of the frangible bullet.

We designed our bullets to open easily on impact with a better ability to overcome the force imparted from the animal trying to change it's speed and direction of motion. This results in a much larger window of impact velocity and available shot angles.

 

[Shane Lindsey]

This is so scientific...pick up rifle, shoot rifle, put rifle down...

 

[FEENIX]

Agreed, and to add: The energy goes to work by converting to force. Not all bullets turn their energy into force, or at least not a lot of force. Some are much better than others and need less energy to begin with. How they convert energy to force is highly dependent upon their construction and the mechanics of how they behave terminally.

This is where the terms energy dump and energy transfer come in. As a bullet converts its energy into force, it rapidly loses momentum. If the bullet loses all its momentum from producing a huge amount of force, it typically doesn't exit. Typically, the higher the rate of momentum lost, the more force is produced and more wounding occurs. That said, you still want to balance it all out so that it occurs within the chest cavity and does the most damage to the vitals. You don't want the bullet to lose all its momentum on or near the surface, for example.

Also, the more momentum the bullet still has, the more force it's still producing. If it produces a ton of force, but simply doesn't lose it all at a rate higher than the speed its traveling, it'll still exit, which we see still with certain soft constructed lead core bullets in certain scenarios.

Ultimately, knowing how the particular bullet you're wanting to use coverts energy into force is what you should focus on and will be much more helpful than going with just a basic rule of thumb on minimum energy. There are many bullets out there that will produce excellent wounding with well under 1000ft-lbs of energy. That's because they're highly efficient at converting energy into force. Conversely, there are many bullets out there that are not efficient at converting energy into force or don't convert very much of it into force.

Frangible bullets are very efficient and effective at converting energy into force. Getting that proper balance though is crucial, and achieved by having sufficient starting mass and not placing the shot in an area where the amount of impact resistance is too much for the impact velocity. But adequate amount of mass at the start can really help with that, as does adjust shot placement for close range shots. A well-constructed and properly selected frangible mono can be very effective as well, to be fair.

Agreed! Sir Isaac Newton was a genius. He figured it out in the 16th century, and the ballisticians/firearms industry today capitalize on; the same knowledge base that helped them design bullets/firearms.

 

[RockyMtnMT]

And a deeper thinker.

 

[Petey308]

Force is kind of a new term brought into terminal performance discussion.

This is false. It's been around forever. Perhaps it's new to this discussion and forum, but it's not anything new in regards to terminal ballistics. It's basic physics.

The energy from a bullet is relatively small but highly focused allowing it to force a small portion of the target to move. The target also contains force.

Yes, Newton's Third Law of Motion tells us about action/reaction. It's why gravity doesn't crush us all. But you can still overcome opposing force by exerting more than the object can hold up to. That's what a bullet is doing upon impact with an animal.

The bullets ability to overcome the force to change direction and velocity imparted on it by the target seems to me to be more important when it comes to predictable repeatable terminal performance. Highly frangible bullets have little ability to overcome the force imparted by the animal. This is the reason they fall short on larger harder targets. This is the reason they have a narrower window of velocity they will function well in.

This is because mass is a crucial part of the equation. If there is insufficient mass to start, there will be an insufficient amount of mass retained after overcoming the opposing force. It's not hard to account for this though, if you understand it. And when you do understand it and apply it to your bullet selection, you actually produce a very broad window of velocity that they function well in and you don't NEED hyper velocities to achieve those desired results.

Particularly higher velocity impacts, because the force imparted on the bullet is increased increasing the potential to destruct or fail. Force is the reason that hunters using highly frangible bullets must be careful about shot placement, because they often can't overcome the increased force from heavy muscle and bone impacts. When these shots where high amounts of force causes frangible bullets to fail is when those who advocate the user of frangible bullets will explain that it was not a failure of the bullet but shooter error. The shooter should have known the limitations of the frangible bullet.

This is misleading and in an obvious effort to downplay the competition. Even tough constructed bonded bullets and other monos can suffer and not perform well in these conditions and this given scenario. To imply hunters don't actually need to understand bullet construction and terminal ballistics is unwise and irresponsible. To imply there's a product that makes it feasible and acceptable to be ignorant is also unwise, irresponsible, and it's not true.

With sufficient starting mass, and proper shot placement and balanced MV for the particular bullet and the particular hunt, as well as proper shot placement for the particular scenario, you'll be just fine and the force from the bullet increases wounding and results in more consistent quick and clean kills. Expecting hunters to have this ability and knowledge is not unrealistic.

As much as a particular manufacturer would love to have their product be the only one everyone uses, that's never going to happen. So we should be teaching bullet construction and terminal ballistics as a whole to the hunting community so that each hunter has the best potential for success with whatever bullet they chose to use.

 

[cabelasken]

When I select a bullet for hunting, I look for wound channel(s), penetration, accuracy, and last BC. Specifically, the wound channel should be 4 to 6 inches in diameter from start to finish, and needs to penetrate at least 15 to 18 inches no matter what angle or structure it hits. I limit my range to where impact velocity is at least 2100 FPS.I do not want to see a lot of bloodshot meat beyond the 4 to 6 inch wound channel. The monos have produced this performance and I have exclusive use themn for the past 15 years

 

[Majestic 6.5]

Yes, even big bull elk can be killed with small caliber rifles, but not reliably. I have seen a lady kill a bull with a .243, but it took 3 hits to bring him down. I've seen a guy kill a bull with a 6.5 prc, but again 3 shots to the chest before he went down.
I have a bunch of rifles, but I would reach for my .300 WM or 28 Nosler for an elk hunt. Maybe take my 7 mag as a backup/spare rifle, but not my 6.5 prc or .270 as I have better choices.
I bet the % of wounded/got away elk is higher for 6.5 Creedmore than .300 WM if the hunter is proficient.

I've seen a .243Ai with a 117 berger VLD drop an elk at 800 yards. Bullet placement is everything. A 50 cal. BMG fmj will pencil game with out expansion but a well placed shot with a properly constructed projectile speaks volumes. I don't advocate using a .243 for Elk but it's been done many times with just one round.

 

[Majestic 6.5]

I've seen a .243Ai with a 117 berger VLD drop an elk at 800 yards. Bullet placement is everything. A 50 cal. BMG fmj will pencil game with out expansion but a well placed shot with a properly constructed projectile speaks volumes. I don't advocate using a .243 for Elk but it's been done many times with just one round.

I believe if a well placed bullet expands and penitrates enough to sever the arteries above the top of the heart cutting off the blood pressure, the animal will drop in it's tracts just like humans with low blood pressure. Energy and Bore diameter mean

 

[memtb]

I've seen a .243Ai with a 117 berger VLD drop an elk at 800 yards. Bullet placement is everything. A 50 cal. BMG fmj will pencil game with out expansion but a well placed shot with a properly constructed projectile speaks volumes. I don't advocate using a .243 for Elk but it's been done many times with just one round.

Nobody with a semblance of intelligence hunts with a sharply pointed, non expanding bullet. Now if you'd care to make that a wide metplat bullet…..my money will be on the 50 cal.

We should be realistic in our discussions! memtb

 

[Majestic 6.5]

Nobody with a semblance of intelligence hunts with a sharply pointed, non expanding bullet. Now if you'd care to make that a wide metplat bullet…..my money will be on the 50 cal.

We should be realistic in our discussions! memtb

Might as well use a grenade launcher

 

[Marky_mark]

I've seen a .243Ai with a 117 berger VLD drop an elk at 800 yards. Bullet placement is everything. A 50 cal. BMG fmj will pencil game with out expansion but a well placed shot with a properly constructed projectile speaks volumes. I don't advocate using a .243 for Elk but it's been done many times with just one round.

Theres probably five times as many that have run away, never to be seen again though

 

[Maol]

I still prefer the selection and use of two bullets. One bullet is for game animals that don't come equipped with teeth, fangs, and claws and the high propensity to maim or kill me - and is selected with the focus on long distance shots. This bullet has to shoot very accurately out of my rifle to make good hits at long distances.

The second bullet is for dangerous game and non-dangerous game at closer ranges. Say from the muzzle out to ~350yds. The primary focus on this bullet is reliability of terminal performance inside the animal. This is the bullet I'm betting my life on in short range encounters with bears or any other game animal that might try to kill me. This bullet is also a great performer on non-dangerous game out to ~350yds, killing quickly and normally with less bullet-caused meat damage than my long range bullet would at the closer ranges. Accuracy is a minor consideration when selecting this second bullet, because almost any decent bullet out of any decent rifle is accurate enough to kill deer-sized game at these closer ranges.

The above is what I figured out as well. The magic do it all bullet is a unicorn.

I hunt for meat and wasting it is aggravating. The grenade effect at close range is an unnecessary meat waster. Solution use a bullet that works in the 0-400 range.

Obviously not being able to hit the terminal point with terminal effect at a greater distance is a meat waster too, so use a second bullet and load.

It's easy to understand, high BC bullets slip right thru animals just like the air. If they don't change shape in the animal, you'll likely be aggravated too. Not enough terminal effect. For this second bullet a high BC bullet is required to get you there, but it must have enough energy to change shape for its design to impart terminal effect.

As others have said, if you intend one rifle to do as per the OP, 0-750 yards including Elk, a 300 or bigger Magnum is a good bet.

 

[ncwg2boatguy]

Here is a link to a physics study of this very subject. It is difficult dry reading, but quite interesting if you are really wanting to know how it works. I read the whole thing a few years ago and it took me a couple of full days of reading. Very good read.

Terminal Ballistics

Steve

Excellent article