bullet weight vs speed and energy

[Rattle'em up]

You see it alot in ballistic tables...lighter faster bullets carrying more energy than slower and heavier. I was always under the impression that slower and heavier was best for busting through heavy boned animals. Now I guess you could say that bullet placement is the key word here but the farther down range the bullet travels the less energy it has and the more room for error. But even so I would have to say that the heavier bullet will carry it's retained energy further through heavy boned animals than light bullets.

[Ron AKA]

I think the biggest single factor after energy available at impact is how well the bullet controls expansion, and retains the original weight. Barnes claim their bullets retain 100% of the original weight, but still open up to do damage. If it is true, that is certainly what you want.

Ron

[just_a_car]

It really comes down to the physics, bear with me here...

Kinetic energy is what they list as "muzzle energy", using the muzzle velocity and the bullet weight. The equation is as follows for kinetic energy:

Energy = 1/2 * Mass * (Velocity)^2

Because velocity is squared in that equation, if you double the velocity, the energy is multiplied by 4, while if you double the mass, the energy is simply doubled.

EX:

Energy of 55 grain (0.00356394005 kg) .223 bullet traveling at 3000 fps (914.4 m/s):

• E = 1/2 * .0356 kg * (914.4 m/s)^2 = 1489.95 kg*(m/s)^2 = 1489.95 Newton-meter (N*m) = 1098.9 ft*lb

Energy of 230 grain (0.0149037493 kg) .45ACP bullet traveling at 850 fps (259.08 m/s):

• E = 1/2 * .0149 kg * (259.08 m/s)^2 = 500.19 N*m = 368.9 ft*lb

What we're really looking at when we think about busting through animal hide and bone is momentum (given by the variable P):

P = Mass * Velocity

EX:

Momentum of 55 grain (0.00356394005 kg) .223 bullet traveling at 3000 fps (914.4 m/s):

• P = .0356 kg * 914.4 m/s = 1489.95 kg*m/s = 3.259 Newton (N) = 0.73 lb

Momentum of 230 grain (0.0149037493 kg) .45ACP bullet traveling at 850 fps (259.08 m/s):

• P = .0149 kg * 259.08 m/s = 3.871 N = 0.87 lb

Do note that the momentum of the heavier bullet going much, much slower is greater than the lighter bullet traveling over three times faster.

The above numbers may not sound like much, but remember, those weights are being applied to a very small area at the tip of the bullet (read as pounds/sq. in. = PSI) and the PSI being applied looks something like this (remember your car tire is around 32 PSI and the force of a "blow-out" is not something to scoff at):

• PSI of 55 grain bullet at tip (tip is about 1/3 width of .224 bullet): .73 lb / (~0.004386 sq. in.) = 166 PSI

• PSI of 230 grain bullet (tip is about 1/3 width of .451 bullet): .87 lb / (~0.01767 sq. in.) = 49.23 PSI

I am going to go out on a limb and guess that the above pressures on the tips of the bullets is one of the reasons that, with ball ammo, the .223 bends or breaks apart while the .45 holds it's basic shape and stays intact.

There is an excellent article on this found here: GS CUSTOM BULLETS - Momentum v. Energy

[Ron AKA]

You are speaking my language, but I'm not immediately convinced. Energy is energy. It has to be dissappated (unless the bullet goes right through, or blows up in the skin or on the first bone, and that is an issue with the bullet design). I will read the article and respond when fully digested! If I recall correctly, momentum is just MV while energy is MV*2. Momentum would be important if the issue was to "knock down" the game, or physically move it. I think that is just a hold over from the old days when the physics of the issue was not really understood. You do not "knock down" game, you inflict tissue damage... to in particular to the lungs (if you hit the target), and the game dies from lack of oxygen. If that were not the case then the archery guys may as well not go out to hunt.

Ron

[Rattle'em up]

Originally Posted by just_a_car

It really comes down to the physics, bear with me here...

Kinetic energy is what they list as "muzzle energy", using the muzzle velocity and the bullet weight. The equation is as follows for kinetic energy:

Energy = 1/2 * Mass * (Velocity)^2

Because velocity is squared in that equation, if you double the velocity, the energy is multiplied by 4, while if you double the mass, the energy is simply doubled.

EX:

Energy of 55 grain (0.00356394005 kg) .223 bullet traveling at 3000 fps (914.4 m/s):

• E = 1/2 * .0356 kg * (914.4 m/s)^2 = 1489.95 kg*(m/s)^2 = 1489.95 Newton-meter (N*m) = 1098.9 ft*lb

Energy of 230 grain (0.0149037493 kg) .45ACP bullet traveling at 850 fps (259.08 m/s):

• E = 1/2 * .0149 kg * (259.08 m/s)^2 = 500.19 N*m = 368.9 ft*lb

What we're really looking at when we think about busting through animal hide and bone is momentum (given by the variable P):

P = Mass * Velocity

EX:

Momentum of 55 grain (0.00356394005 kg) .223 bullet traveling at 3000 fps (914.4 m/s):

• P = .0356 kg * 914.4 m/s = 1489.95 kg*m/s = 3.259 Newton (N) = 0.73 lb

Momentum of 230 grain (0.0149037493 kg) .45ACP bullet traveling at 850 fps (259.08 m/s):

• P = .0149 kg * 259.08 m/s = 3.871 N = 0.87 lb

Do note that the momentum of the heavier bullet going much, much slower is greater than the lighter bullet traveling over three times faster.

The above numbers may not sound like much, but remember, those weights are being applied to a very small area at the tip of the bullet (read as pounds/sq. in. = PSI) and the PSI being applied looks something like this (remember your car tire is around 32 PSI and the force of a "blow-out" is not something to scoff at):

• PSI of 55 grain bullet at tip (tip is about 1/3 width of .224 bullet): .73 lb / (~0.004386 sq. in.) = 166 PSI

• PSI of 230 grain bullet (tip is about 1/3 width of .451 bullet): .87 lb / (~0.01767 sq. in.) = 49.23 PSI

I am going to go out on a limb and guess that the above pressures on the tips of the bullets is one of the reasons that, with ball ammo, the .223 bends or breaks apart while the .45 holds it's basic shape and stays intact.

There is an excellent article on this found here: GS CUSTOM BULLETS - Momentum v. Energy

Wow , you did your homework . Thanks for the info.I appreciate it. I will check it out.

[mtm1]

Big bullet (Barnes TSX ) at high speed. Problem solved.

[300RUM]

Um.. Im gettin a headache.. I bring nothing to the table.

[sell33]

Ok so is more energy better or no? this question has been bugging me for awhile. I have been researching a bit but im still not convinced of anything. Now it seems to me that if something is hit with more energy its gonna hurt a lot more. Obviously a lot depends on bullet type and what not. But, isn't say 1000 pounds of energy in a bullet essentially the same as say dropping a thousand pound weight on that one little spot. I don't know if that is a similar concept or not. I suppose bullet type is basically the best deciding factor in the amount of damage done, that and shot placement of course. This is all just so confusing lol....

[big boomer]

Its the old Elmer Keith vs Roy Weatherby deal. The army went smaller and faster because it takes four guys to handle a wounded man, thats why the .223. Nobody is ever slightly wounded by a 45/70, the debate has gone on for decades.

[Ron AKA]

I read through the article, and I believe the author is totally incorrect in his use of momentum in preference to energy. I suspect he is just doing this because he likes heavier slower bullets in preference to lighter faster ones, just because it is his preference. There is no way science can support what he is saying in his rambling article that really does not say much. Energy is energy and that is what does the damage. He is correct in that terminal velocity and retained weight is important. Using all the energy comes down to the appropriate bullet design, and it requires a different bullet for high velocity cartridges than for low velocity ones. A 308 needs a lighter jacket so it can expand with the slower velocities that this cartridge produces. On the other hand a 300 RUM will need a heavier jacket so it does not blow up and fragment on impact. The Nosler partition bullet is a compromise solution, with a light front end and a rear section that is nearly guaranteed to hold together. For that reason it will tolerate a wider range of velocities. The solid copper bullets from Barnes and possibly the company of the author of the article, may have those advantages as well. It probably can be argued that a regular jacketed bullet can be a compromise as well if the jacket thickness and strength is controlled from front to back of the bullet with much more strenth in the back 2/3's or so.

It comes down to energy at impact, placement, and bullet design. Within reason bore size and bullet weight are much less important factors.

Ron

Originally Posted by just_a_car

It really comes down to the physics, bear with me here...

Kinetic energy is what they list as "muzzle energy", using the muzzle velocity and the bullet weight. The equation is as follows for kinetic energy:

Energy = 1/2 * Mass * (Velocity)^2

Because velocity is squared in that equation, if you double the velocity, the energy is multiplied by 4, while if you double the mass, the energy is simply doubled.

EX:



Energy of 55 grain (0.00356394005 kg) .223 bullet traveling at 3000 fps (914.4 m/s):

• E = 1/2 * .0356 kg * (914.4 m/s)^2 = 1489.95 kg*(m/s)^2 = 1489.95 Newton-meter (N*m) = 1098.9 ft*lb

Energy of 230 grain (0.0149037493 kg) .45ACP bullet traveling at 850 fps (259.08 m/s):

• E = 1/2 * .0149 kg * (259.08 m/s)^2 = 500.19 N*m = 368.9 ft*lb

What we're really looking at when we think about busting through animal hide and bone is momentum (given by the variable P):

P = Mass * Velocity

EX:



Momentum of 55 grain (0.00356394005 kg) .223 bullet traveling at 3000 fps (914.4 m/s):

• P = .0356 kg * 914.4 m/s = 1489.95 kg*m/s = 3.259 Newton (N) = 0.73 lb

Momentum of 230 grain (0.0149037493 kg) .45ACP bullet traveling at 850 fps (259.08 m/s):

• P = .0149 kg * 259.08 m/s = 3.871 N = 0.87 lb

Do note that the momentum of the heavier bullet going much, much slower is greater than the lighter bullet traveling over three times faster.



The above numbers may not sound like much, but remember, those weights are being applied to a very small area at the tip of the bullet (read as pounds/sq. in. = PSI) and the PSI being applied looks something like this (remember your car tire is around 32 PSI and the force of a "blow-out" is not something to scoff at):

• PSI of 55 grain bullet at tip (tip is about 1/3 width of .224 bullet): .73 lb / (~0.004386 sq. in.) = 166 PSI

• PSI of 230 grain bullet (tip is about 1/3 width of .451 bullet): .87 lb / (~0.01767 sq. in.) = 49.23 PSI

I am going to go out on a limb and guess that the above pressures on the tips of the bullets is one of the reasons that, with ball ammo, the .223 bends or breaks apart while the .45 holds it's basic shape and stays intact.

There is an excellent article on this found here: GS CUSTOM BULLETS - Momentum v. Energy

[turner]

I'll only promise you this.....Punch a hole in a good spot... have the bullet pass completely through, and have that bullet open to over 1/2" and you will find your deer/caribou/moose/bear! Now, start with a round of...say .30 to .338 and you'll never have a problem, PERIOD! Very simple.

[Ron AKA]

Originally Posted by turner

I'll only promise you this.....Punch a hole in a good spot... have the bullet pass completely through, and have that bullet open to over 1/2" and you will find your deer/caribou/moose/bear! Now, start with a round of...say .30 to .338 and you'll never have a problem, PERIOD! Very simple.

Think about an animal 120" tall or more, and weighing 1000-1500 lbs..., and ask if it makes sense that a hole 0.036" larger or smaller makes a significant difference?

Ron

[AKHunter]

Damn, how many critters are 10 feet tall ? I can think only of a giraffe . Maybe an elephant ?

Ok , after reading that article I have to agree for the most part on what he says. Keep in mind there were some tongue-in-cheek statements of his own admission in there.

My handloads reflect much of what he says about loading an all-around bullet weight and those tend to lean on the heavier side of choices. .338wm, 225 grain bullet 2800 fps, sometimes a 250gr bullet at 2700 .30-06, 180 gr bullet 2650 fps. Each pack a whoopin and each can easily take down a critter at 300 yards ( or more should I choose to shoot that far). Each have taken 1000 to 1600lb critters with ease.

Whatever the discussion and whatever the "paper" says I opt for the heavier bullets on big critters. The heavier the animal, the heavier, tougher the bones. A hyper velocity lightweight bullet hitting heavy bone will loose momentum rapidly, a heavy slower moving bullet will smash through with authority and cause far greater damage as it continues onward. "Energy" listed in a ballistic table is math plain and simple. I'll take a larger diameter, heavier, slower bullet on BIG game every time. I have'nt lost that argument to a critter yet !

Each side has valid points but, I leave the hyper velocity, small diameter projectiles to the paper and the small game.

This subject comes up frequently only it is worded differently each time. I think the real way to solve this debate is to have the fans of the hyper velocity, small diameter cartridges come to alaska or go to africa and hunt the big dangerous game vs the ones who favor the heavier slower cartridges and count casualties from there on out. I know where my money is !

[Onesonek]

Personally, I prefer to go with more momentum. While they all work in conjunction with one another, speed and energy alone are not enough. Just take for instance a .30cal., a 110 gr has way more velocity and about the same if not slightly more energy than say a 180 gr.. But without the momentum that speed and energy isn't going to do as much damage. Pretty much already stated. There is something to said for hydrostatic shock, but likewise a bullet with some momentum and speed throughout the entire time it's in the animal creates more shock to the CNS (central nervous system), this fact is often overlooked.
As I stated, I prefer a little extra asurance on the penetration side. When I choose a bullet for a given caliber, I look at what I'm using it for game wise, hunting conditions, and the worst case senario. If I don't need it fine, but if I do and don't have it loaded, it's my fault.

Dave

[Farmer]

I believe its energy that does the damage.
Its simple really, ask Einstein.

E=MC2
Energy = Mass X (Velocity squared)

So in simple terms if its 250grains and is going 900pfs its energy is 250 x (900x900)= 202,500,000.
So to get a 55gn to make the same number it must go 2000fps.
So to get a 150gn to make the same number it must travel at 1500fps
A 223 does about 3000fps so the math is 55 x (3000x3000)= 495,000,000


Soooooooooooooo, if energy is the important thing the 223 seems pretty powerful!

[just_a_car]

Farmer, you can either go back to the first page and read my post or just go back and read your high school physics book, either way, you'll see you got that a little 'off'.

That equation is: Energy = mass * (Speed of light)^2
That equation was meant for conversion of mass to energy (literally, as in nuclear fission or fusion) or determining the energy of a particle of matter, such as a single atom or subatomic particle.

The equation for kinetic energy is: Energy = 1/2 * mass * (velocity)^2
...as was explained in my post. Not to mention you never mention what units you're using for mass, velocity or energy, so the numbers are kind of meaningless.

[nathangdad]

Great job on the physics.

But consider the fact the bullet weight versus speed and energy
must give way to the cartridge with which you can accurately place the bullet. A miss with a Weatherby super screamer is of no value.

Somehow, in looking back, I feel I have seen multitudes of overgunned,
flinching shooters.

I know this will draw some flak for being off subject but to me it
is an important thought.

Good luck and good shooting to all the posters.

[irish murphy]

Well people should HTFU and not be scared of a bit of recoil.

[elmer fudd]

power is good but if it is heavy it wont move around in wind as much

[samuel]

Originally Posted by sell33

Ok so is more energy better or no? this question has been bugging me for awhile. I have been researching a bit but im still not convinced of anything. Now it seems to me that if something is hit with more energy its gonna hurt a lot more. Obviously a lot depends on bullet type and what not. But, isn't say 1000 pounds of energy in a bullet essentially the same as say dropping a thousand pound weight on that one little spot. I don't know if that is a similar concept or not. I suppose bullet type is basically the best deciding factor in the amount of damage done, that and shot placement of course. This is all just so confusing lol....

The way it works is,if you have a bullet that developes 2800lbs energy and an animal that takes 200lbs energy to penetrate through,you only displace 200lbs energy.If the bullet expands,the energy necessary to penetrate increases,increasing the energy dispersed.If it fragments,it may disperse all of its energy but only in a limited area,leaving the rest of the animal very much alive.If it expands to a point that it is dispersing considerable energy but retaining enough to continue penetration,then it is doing damage clear across the animal.Hydrostatic shock is the small amount of energy dispersed as the bullet penetrates.The faster the bullet is going,the more hs.The more expansion of the bullet the more primary tissue damage.Hydrostatic shock is minor permanent damage compared to primary wound channel damage and may heal all togather if the animal lives through the primary damage done in the original wound channel.So,I still believe in big,heavy bullets,tearing the hel* out of everything they touch not depending on hydrostatic shock which may or may not happen to a degree that is fatal.This is xperience.It's what has always worked. sam.