Bullet momentum VS. Ftlbs energy
- Thread starter BigBore45
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Can I ask what is the intended purpose of the comparison? It is just for general knowledge or are you looking for a specific load for hunting that will do a better job? There are so many variables in what you are asking that if you give a specific scenario it will be easier to do a comparison. Even with the same momentum and speed, different loads that are different sizes will deform diferently and will take different trajectories which at the end will tell how much penetrate or which organs they hit. If you want a definitive penetration or specific damage done you can get as many answers to this as type of ammo available.(FML,JHP,frangible,etc.)
i would like to know a difference between things like a 45 colt 200 grain bullet with 400 ftlbs of energy vs. 45 colt 300 grain with 400ftlbs of energy. or even a 9mm 124 gr. with 350 lbs of energy vs. a 44 special 240 gr. with 350 ftlbs of energy. or if there is even a difference? looking for a good self defense load is the purpose. i figured for people that load this would be the best place to put it.
i will be using lead cast bullets. i make mine in flat nose or hollow point. for this i would run wheel weights and harden the base to hold together. double lubed, lube and size then liquid alox after. hate lead in my barrels.
i did test today for a gun and in .45 Colt i have a 200 gn. hollow point running 955FPS. just curious how that stacks up when it hits a real target or if the ftlbs is just kinda B.S.
i did test today for a gun and in .45 Colt i have a 200 gn. hollow point running 955FPS. just curious how that stacks up when it hits a real target or if the ftlbs is just kinda B.S.
blarby
Member
http://www.1728.org/energy.htm
Knock down power is a myth, and a bad one.
Very few, and certainly nothing in 45colt, handguns, will produce hydrostatic shock.
Beyond that, you have CNS hits. Beyond that, you have wound cavity size, and vital system disruption.
Test your loads on a medium of your choice, and observe the effects.
Many a man has died from 45 caliber bullets doing far less than 900 fps. Im guessing most of them were in the 200+ grain category.
Knock down power is a myth, and a bad one.
Very few, and certainly nothing in 45colt, handguns, will produce hydrostatic shock.
Beyond that, you have CNS hits. Beyond that, you have wound cavity size, and vital system disruption.
Test your loads on a medium of your choice, and observe the effects.
Many a man has died from 45 caliber bullets doing far less than 900 fps. Im guessing most of them were in the 200+ grain category.
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thanks for the web site. but this is what im trying to find out, why heavy bullet for bowling pins, or why light bullets for comp shooting???
so with that calc. a .500 cal 500 gr. bullet at 600 fps 400 ftlbs is going to perform the same as a .22 cal 55 gr. bullet at 1800FPS 400 ftlb sthat is not how it works in the field?
why not carry a base ball and throw it at game instead of shooting it with a .22 short. that is the point of this thread, and to get loading info for my carry gun. go heavy for weight loads or light and fast?
so with that calc. a .500 cal 500 gr. bullet at 600 fps 400 ftlbs is going to perform the same as a .22 cal 55 gr. bullet at 1800FPS 400 ftlb sthat is not how it works in the field?
why not carry a base ball and throw it at game instead of shooting it with a .22 short. that is the point of this thread, and to get loading info for my carry gun. go heavy for weight loads or light and fast?
Energy tells you the potential for damage. There's no guarantee you'll apply it to the target or that 500 ft-lbs is more effective than 400 ft-lbs. But 1000 ft-lbs should be more effective than 100 ft-lbs. Energy goes up with velocity squared, so light fast bullets can have some impressive energy numbers, but may penetrate poorly. But "knock down" power does seem to be better once a certain velocity level is reached (around 2000 fps or so). High velocity also benefits armor penetration (thin and hard armor, like metal).
Momentum tends to tell you penetration potential, but you have to factor in bullet diameter. Power factor (weight * velocity / 1000) and Taylor Knock Out formulas are momentum based. Bullet shape also affects penetration - a flat nose penetrates less but does more tissue damage. A 45 caliber bullet with a power factor of 250 will penetrate more than a 45 bullet with a 200 power factor if the bullet noses are the same shape.
Knock down on people and even animals with handguns is an iffy thing. Shot placement is more important. Bullet diameter is also important, but an expanding bullet isn't guaranteed to expand, and an expanded bullet doesn't penetrate as far, so you need to test these to make sure you have a good balance of penetration and expansion for the intended target. You want the biggest hole, with a large flat front, that penetrates to the vitals, and personally I want a bullet to completely penetrate the target.
Momentum tends to tell you penetration potential, but you have to factor in bullet diameter. Power factor (weight * velocity / 1000) and Taylor Knock Out formulas are momentum based. Bullet shape also affects penetration - a flat nose penetrates less but does more tissue damage. A 45 caliber bullet with a power factor of 250 will penetrate more than a 45 bullet with a 200 power factor if the bullet noses are the same shape.
Knock down on people and even animals with handguns is an iffy thing. Shot placement is more important. Bullet diameter is also important, but an expanding bullet isn't guaranteed to expand, and an expanded bullet doesn't penetrate as far, so you need to test these to make sure you have a good balance of penetration and expansion for the intended target. You want the biggest hole, with a large flat front, that penetrates to the vitals, and personally I want a bullet to completely penetrate the target.
thanks suemark. it makes sense how to you do these figures. i am at a loss i have a 45 colt and have been trying loads. im iffy on a 200 grain at .454 cal. the penetration would be my worry. i know however a 260 gr. at the same ftlbs of energy will penetrate better but will it cause as much damage?
i see that was i was looking for has been found. Taylor Knock Out factor. thanks guys!
her fore everyone else: http://www.reloadammo.com/tkofactor2.htm
her fore everyone else: http://www.reloadammo.com/tkofactor2.htm
Mad Chemist
Member
Shot placement is king. Worrying about a few ft lbs is majoring in the minor stuff.
There are certain velocity minimums that must be maintained to penetrate skin/hide. I'd never want to go below 500 FPS impact speed. In the old Thompson-Lagarde study (where they we basically trying to document how the 45 ACP was best instead of trying to find out if it was), they mention a certain velocity step has having more obvious damage impact. This was around 800 fps. I think you'll see steps like this because of the energy increase with velocity squared. So a given bullet that impacts at 500 fps will be less dramatic than the same at 800 fps, and more dramatic at 1200 fps, and even more impressive at 1600 fps.
A 200gr .454 bullet at 800 fps that doesn't expand will easily penetrate a person (assuming gelatin penetration, not bones). Heck, a 45 round ball at 700 fps easily penetrates a person and those only weigh 141 grains each (but they slow down quickly). If you're using a hollowpoint, they tend to need a bit more speed to expand, and the more they expand the less they penetrate. If you use the old Speer 200gr "flying ash tray" JHP, I'd be afraid to push those faster than 900 fps as they tend to over expand and don't penetrate enough. But at 700 fps they may not expand at all.
A 200gr .454 bullet at 800 fps that doesn't expand will easily penetrate a person (assuming gelatin penetration, not bones). Heck, a 45 round ball at 700 fps easily penetrates a person and those only weigh 141 grains each (but they slow down quickly). If you're using a hollowpoint, they tend to need a bit more speed to expand, and the more they expand the less they penetrate. If you use the old Speer 200gr "flying ash tray" JHP, I'd be afraid to push those faster than 900 fps as they tend to over expand and don't penetrate enough. But at 700 fps they may not expand at all.
Mad Chemist
Member
The 200gr Flying Ashtray can be downright nasty at normal .44spl velocities around 800fps. Of course this implies that one can actually hit the target
.
.well lets assume bones. they are there. thats why i lean towards hand casted lead bullets. soft in front, hard at the back. great i didnt hit the bone, it mushrooms and contunues on. o no i hit a heavy bone it mushrooms and either fragments and the hard back keeps going or it mushrooms and the hard back keeps going. i would still like to know what it takes to in terms of my cal and bullets and bullet weight to get threw a bad placed shot.
that .45 will have a decent penetration and stopping power regardless of the different types of bullets used. You said that you are using lead hollowpoints and the average speed you will get and impact power would be enough for most defensive situations. Also you have to take into account what distance do you plan to use in a defensive situation. If it is inside your house or in a personal held conflict in the street , most of them happen at less than 10 yards distance. If you try to shoot at a longer distance ,you should assume that it is better to not shoot at all and take a better cover position. And also if you shoot somebody at a bigger distance you have more possibilities of being charged with manslaugther.
CZCCW Thanks for the reply, I know that the .45 will have decent stopping power. I'm looking at working a load up that i feel is the best, the more knowledge the better. I am however, not asking for when to shoot or how far I personally can shoot safely or by law as this information can and will be applied to hunting situations as well.
ljnowell
Member
I started a thread on bowling pin loads the other day. In pin shoots a heavy bullet is usually desired.
In 45 a 200gr bullet at say 1000fps will make more energy than a max loaded 255 gr bullet, but have less momentum.
Many seasoned pin shooters will say that ft lbs of every aren't as important as momentum.
I'm not a scientist but I am shooting in a new start up pin league starting this month. I guess we will see.
In 45 a 200gr bullet at say 1000fps will make more energy than a max loaded 255 gr bullet, but have less momentum.
Many seasoned pin shooters will say that ft lbs of every aren't as important as momentum.
I'm not a scientist but I am shooting in a new start up pin league starting this month. I guess we will see.
i know i commented on your thread, thats what got me thinking on this. it is true the heavy bullet with less ftlbs does knock pins down "better" i am wanting to know why and how this is measured. Good luck on the shoot, hope its a blast.
blarby
Member
It would appear you need some assistance on terminal ballistics. Please, let me oblige, now that I have more time :
http://www.physicsclassroom.com/class/momentum/u4l1a.cfm
For bowling pins, you are looking at vector quantity -vs- a stationary object. In this case, the Pin.
If you need a good primer on how all of this math works, it can be found here :
http://staff.hartdistrict.org/glyle/tools/momentum_how_to/Momentum overview.pdf
Illustrates the fallacy of "knock down power" pretty quickly, when you consider the mass of a human in comparison to a bowling pin.
That "mushrooming" you are referring to, all it really does is enlarge the temporary wound cavity, and continue the permanent wound cavity throughout the target.
Neat study on dead human flesh vs bullets :
http://www.researchgate.net/publica...tics_temporary_cavity_effects_in_soft_tissues
( you will need to sign up for that one )
If you trust the FBI's take on the issue :
http://www.firearmstactical.com/pdf/fbi-hwfe.pdf ( run the PDF )
Hornadys take on the issue :
http://www.hornady.com/ballistics-resource/terminal
Probably the must summed up version, care of Hornady :
A scholarly piece.... :
http://www.southampton.ac.uk/~jb3/bullet/gsw.html
Last interesting piece :
http://www.researchgate.net/publica...anics_a_review/links/09e415102cd85f055d000000
Want "knock down power" ? Make a CNS hit- anywhere between the skull, along the spinal column. That will knock them down.
Beyond that, you are essentially perforating for the most damage, hoping to cause unconsciousness either through shock, blood loss, or usually, both.
Those of us who believe we can effectively place CNS hits on moving targets in life or death situations with regularity should opt for ammunition capacity sufficient to allow those shots to be placed. Those of us who do not have this predilliction generally opt for the largest permanent wound cavity possible to facilitate the rapid exsanguination of our target game or assailants. This is pretty much the crux of the "caliber for defense" argument. Not all of it, but it relays the majority of the "science" that most regular folks can understand.
From all of my readings, CNS hits are the exception rather than the norm in fatal gunfights. What generally happens is exsanguination.
For good example : The reliable 12 gauge shotgun using buckshot. The proverbial "knock down" master we see in the movies, and on forums of lesser ilk....
It did not get its reputation ( the basis of all these myths) because it actually flings people across the street, or simply causes them to give up the ghost upon hearing the racking sound of shell into chamber.... it gets that reputation because 9 to 15 30 caliber balls is quite a bit of perforation, and causes RAPID exsanguination. Except at really close distances, most of these projectiles will not exit the body of the target. They often do not break bones, they deform and go around them- although chest and rib breakage is a common occurence.
Each of those pellets is in reality smaller than a 9mm projectile ( .330ish vs .355 ) but 9 to 15 of them at once is a pretty certain show stopper for the target. I say this with certainty as a buckshot hunter who grew up in Michigan. Its the only 1st hand evidence I have, but it was a pretty convincing show to me.
With that said, I think your two pour ( or hardened base ) hollowpoints are a great choice. If it were my defensive piece, I would opt for a 260 grain of that variety- but I would test the bullets very carefully in media to make certain that the one that finds its mark is going to do what its supposed to do. Casting solid bullets isn't very hard. Casting reliable hollowpoints, is.
I can tell you from experience that you will not get the deployment you want from wheelweight alloy. I would suggest a hard base ( linotype, or harder- perhaps 22-24 BHN ) and a pure lead tip/cavity.
Depending on the speed and quality of the projectile, all of my wheelweight HP's either violently disintegrated shortly after impact OR sailed right on through like a non hollowpoint. There were very few that worked like I mistakenly believed they should have. Through my studies of the bullet, I learned it was not poor bullet manufacturing per se, it was a poor materials choice in that manufacturing.
If you want to learn to cast great HP's, I'd suggest looking up 35whelen. He's here. He can guide you down the path to great HP's with much more experience than I can.
http://www.physicsclassroom.com/class/momentum/u4l1a.cfm
For bowling pins, you are looking at vector quantity -vs- a stationary object. In this case, the Pin.
If you need a good primer on how all of this math works, it can be found here :
http://staff.hartdistrict.org/glyle/tools/momentum_how_to/Momentum overview.pdf
Illustrates the fallacy of "knock down power" pretty quickly, when you consider the mass of a human in comparison to a bowling pin.
That "mushrooming" you are referring to, all it really does is enlarge the temporary wound cavity, and continue the permanent wound cavity throughout the target.
Neat study on dead human flesh vs bullets :
http://www.researchgate.net/publica...tics_temporary_cavity_effects_in_soft_tissues
( you will need to sign up for that one )
If you trust the FBI's take on the issue :
http://www.firearmstactical.com/pdf/fbi-hwfe.pdf ( run the PDF )
Hornadys take on the issue :
http://www.hornady.com/ballistics-resource/terminal
Probably the must summed up version, care of Hornady :
A scholarly piece.... :
http://www.southampton.ac.uk/~jb3/bullet/gsw.html
Last interesting piece :
http://www.researchgate.net/publica...anics_a_review/links/09e415102cd85f055d000000
Want "knock down power" ? Make a CNS hit- anywhere between the skull, along the spinal column. That will knock them down.
Beyond that, you are essentially perforating for the most damage, hoping to cause unconsciousness either through shock, blood loss, or usually, both.
Those of us who believe we can effectively place CNS hits on moving targets in life or death situations with regularity should opt for ammunition capacity sufficient to allow those shots to be placed. Those of us who do not have this predilliction generally opt for the largest permanent wound cavity possible to facilitate the rapid exsanguination of our target game or assailants. This is pretty much the crux of the "caliber for defense" argument. Not all of it, but it relays the majority of the "science" that most regular folks can understand.
From all of my readings, CNS hits are the exception rather than the norm in fatal gunfights. What generally happens is exsanguination.
For good example : The reliable 12 gauge shotgun using buckshot. The proverbial "knock down" master we see in the movies, and on forums of lesser ilk....
It did not get its reputation ( the basis of all these myths) because it actually flings people across the street, or simply causes them to give up the ghost upon hearing the racking sound of shell into chamber.... it gets that reputation because 9 to 15 30 caliber balls is quite a bit of perforation, and causes RAPID exsanguination. Except at really close distances, most of these projectiles will not exit the body of the target. They often do not break bones, they deform and go around them- although chest and rib breakage is a common occurence.
Each of those pellets is in reality smaller than a 9mm projectile ( .330ish vs .355 ) but 9 to 15 of them at once is a pretty certain show stopper for the target. I say this with certainty as a buckshot hunter who grew up in Michigan. Its the only 1st hand evidence I have, but it was a pretty convincing show to me.
With that said, I think your two pour ( or hardened base ) hollowpoints are a great choice. If it were my defensive piece, I would opt for a 260 grain of that variety- but I would test the bullets very carefully in media to make certain that the one that finds its mark is going to do what its supposed to do. Casting solid bullets isn't very hard. Casting reliable hollowpoints, is.
I can tell you from experience that you will not get the deployment you want from wheelweight alloy. I would suggest a hard base ( linotype, or harder- perhaps 22-24 BHN ) and a pure lead tip/cavity.
Depending on the speed and quality of the projectile, all of my wheelweight HP's either violently disintegrated shortly after impact OR sailed right on through like a non hollowpoint. There were very few that worked like I mistakenly believed they should have. Through my studies of the bullet, I learned it was not poor bullet manufacturing per se, it was a poor materials choice in that manufacturing.
If you want to learn to cast great HP's, I'd suggest looking up 35whelen. He's here. He can guide you down the path to great HP's with much more experience than I can.
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When you first mentioned "knock down power", I thought you were asking the typical mall ninja question about "stopping power". Now I know that you really mean "knock down power" as in knocking over bowling pins!
That is based on momentum, not energy. Momentum is mass of bullet times velocity when it hits the pins. Energy in foot-pounds is 1/2 (mass)*(velocity*velocity). Which means with equal energy bullets, one with 1/4 the mass must have double the velocity. That also means the lighter bullet will only have half the momentum to knock the pin over. Yes a slow moving 50 cal bullet will knock over the pin easier than a needle travelling an near light speed. Listen to the bowling pin shooters. A heavier bullet is better even if it is slower so long as the bullet drop is not excessive at the distances you are shooting. Also note that momentum is pretty much directly related to gun recoil which may lead to flinching and more difficult follow up shots if you are not used to it.
That is based on momentum, not energy. Momentum is mass of bullet times velocity when it hits the pins. Energy in foot-pounds is 1/2 (mass)*(velocity*velocity). Which means with equal energy bullets, one with 1/4 the mass must have double the velocity. That also means the lighter bullet will only have half the momentum to knock the pin over. Yes a slow moving 50 cal bullet will knock over the pin easier than a needle travelling an near light speed. Listen to the bowling pin shooters. A heavier bullet is better even if it is slower so long as the bullet drop is not excessive at the distances you are shooting. Also note that momentum is pretty much directly related to gun recoil which may lead to flinching and more difficult follow up shots if you are not used to it.
blarby
Member
Ok, I had to do this one.....
Needle : Closest one at hand weighed 15 grains
Speed of light : 983,571,056 feet per second
Result :
Momentum 65,455.03921916593
KE : 32,189,841,022,658.223
50 cal bullet (we'll say 750 grains )
Speed : We'll say 2800 FPS- about max speed.
Momentum : 9.316770186335404
KE : 13,043.478260869566
For knocking over pins, or any other object, I'll take light speed ANYTHING. The pin has roughly 7 THOUSAND and 2 HUNDRED TIMES the momentum of the AMAX projectile.
In comparison, a 2000 pound car travelling 60 MPH ( 88 FPS.. groan) is :
Momentum : 5,465.83
KE : 240,496.89
The kinetic energy math is basically parallel to what is publicized for the 50 BMG in terms of ft/#'s of force, so I guess my calculator still mostly works.
Kinda illustrates how the math works, and how the perception of speed and mass in relation to energy is misperceived.
Not a dig at you rocket, just had to do the math to see if I could still even figure it out. Brain damage and all that...
Of course, what happens when either projectile hits the surface is up for debate. If anyone has video of both side by side, I'd love to see it. Until then, its all conjecture.
And one for which im certain there is a notification banner somewhere in Mod land called " Communal Groan Initiated"
Needle : Closest one at hand weighed 15 grains
Speed of light : 983,571,056 feet per second
Result :
Momentum 65,455.03921916593
KE : 32,189,841,022,658.223
50 cal bullet (we'll say 750 grains )
Speed : We'll say 2800 FPS- about max speed.
Momentum : 9.316770186335404
KE : 13,043.478260869566
For knocking over pins, or any other object, I'll take light speed ANYTHING. The pin has roughly 7 THOUSAND and 2 HUNDRED TIMES the momentum of the AMAX projectile.
In comparison, a 2000 pound car travelling 60 MPH ( 88 FPS.. groan) is :
Momentum : 5,465.83
KE : 240,496.89
The kinetic energy math is basically parallel to what is publicized for the 50 BMG in terms of ft/#'s of force, so I guess my calculator still mostly works.
Kinda illustrates how the math works, and how the perception of speed and mass in relation to energy is misperceived.
Not a dig at you rocket, just had to do the math to see if I could still even figure it out. Brain damage and all that...
Of course, what happens when either projectile hits the surface is up for debate. If anyone has video of both side by side, I'd love to see it. Until then, its all conjecture.
And one for which im certain there is a notification banner somewhere in Mod land called " Communal Groan Initiated"
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that's for the reply's. I will read up on this with those links you posted. I would like to stress I think any .45 hunting round is sufficient but I am more into this out of curiosity and insight to casting bullets. thanks again.
after testing this week i have my velocity and my type of bullet. now i will just have to work on bullet performance which i will most like try a few on my own and start a new thread on casting lead bullets. thanks everyone for the reply's!
ljnowell
Member
I have all but decided not to use the 255 grain bullets in my 45ACP bowling pin loads. I think I will take Arch's advice and try some 230 LRN over a big charge of #5.
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