Double Naught Spy
Sus Venator
Which proves when being attacked by an army of 12" steel discs just shy of 2" thick that become ineffective once knocked over, that they can all be readily defeated by the .45 acp or by your little finger.
Why are slow moving heavy bullets considered to be effective?
- Thread starter Hummer70
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someguy2800
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I got the message about big heavy bullets the first time I shot my 444 marlin at steel plates. When you hit the 10" hanging plate at 200 yards with a 270 it rings like a bell and swings about 45 degrees. When you hit it with a 320 grain flat nose gas check cast bullets at 2100 fps it sounds like a sledge hammer hitting concrete and it knocked my target stand over. If you do the math on the ballistics the 270 has more energy when it gets there but it doesn't transfer that energy to the target nearly as effectively.
There’s the 230gr PDX1 45acp from my 4” XD45 that I recovered from a feral pig I shot at about 25-30 yards. Gave the performance earlier in the thread. This is THE bullet I recovered. Looks like my memory was off a little on how it mic’d out though. It was larger than I thought. And those little claws (Talons, sound familiar?) are pretty dang sharp.
This is outdated information and is no longer correct. Modern ammunition design allows good expansion well under this figure.
http://www.brassfetcher.com/Ballistic Gelatin Tests/45 ACP 10 Percent Ballistic Gelatin.html
I'm not sure that being able to knock down a plate that can be pushed over with a little finger is exactly a ringing endorsement of a caliber. Any more than not being able to knock down a plate is an indictment of one. If the round penetrates deeply enough to get to the vitals and expands to a decent frontal area, what difference does it make whether it does or doesn't knock down plates?
denton
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Some approaches to wounding ballistics start by considering energy. This is a difficult path. Energy is conserved, but kinetic energy is transferred into forms that are hard to trace. For example, tissue around the wound channel is stretched and bruised, but snaps back into place. In the wound channel, kinetic energy is converted to crushing and tearing tissue.
Momentum is conserved. This is the easier path to wounding ballistics. Shoot a 38 cast bullet at a metal plate, and the bullet flattens into a pancake but the momentum is conserved.
Physical substances, including flesh and bone, have a maximum bearing pressure. Anything above that pressure will crush them.
Pressure is force per unit area. Divide the force the bullet applies to the target by its frontal area and you have pressure. If the pressure is above the bearing strength of the target, the bullet will continue to penetrate.
The force, and hence the pressure, a bullet applies to the target is equal to the rate at which the bullet is shedding momentum. Hit a bone and the bullet sheds momentum quickly. Exiting the bone, the bullet has less momentum left to shed. Eventually, the bullet does not have sufficient momentum left to apply crushing force to the tissue ahead of it, and it comes to rest.
Hit a bowling pin with a flat-nose, and a lot of momentum is transferred in a hurry.
Momentum is conserved. This is the easier path to wounding ballistics. Shoot a 38 cast bullet at a metal plate, and the bullet flattens into a pancake but the momentum is conserved.
Physical substances, including flesh and bone, have a maximum bearing pressure. Anything above that pressure will crush them.
Pressure is force per unit area. Divide the force the bullet applies to the target by its frontal area and you have pressure. If the pressure is above the bearing strength of the target, the bullet will continue to penetrate.
The force, and hence the pressure, a bullet applies to the target is equal to the rate at which the bullet is shedding momentum. Hit a bone and the bullet sheds momentum quickly. Exiting the bone, the bullet has less momentum left to shed. Eventually, the bullet does not have sufficient momentum left to apply crushing force to the tissue ahead of it, and it comes to rest.
Hit a bowling pin with a flat-nose, and a lot of momentum is transferred in a hurry.
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muzzleblast...
Member
Hummer70,
Thank you for sharing.
Although pistol bullet design and manufacturing this century has improved the reliability of expansion and weight retention; a relatively hard cast, large meplat, semi-wadcutter bullet at moderate velocity has over a century of documented effectiveness. Inevitably it seems, when the subject of through and through penetration is discussed the potential negatives of "over-penetration" become emphasized... and the potential benefits of both "entry and exit wounds" becomes marginalized.
I particularly enjoyed the articles in the last IWBA that discussed the studies on reaction times to a threat and reactions times relative to a string of fire and cessation of a threat.
Thanks again.
Thank you for sharing.
Although pistol bullet design and manufacturing this century has improved the reliability of expansion and weight retention; a relatively hard cast, large meplat, semi-wadcutter bullet at moderate velocity has over a century of documented effectiveness. Inevitably it seems, when the subject of through and through penetration is discussed the potential negatives of "over-penetration" become emphasized... and the potential benefits of both "entry and exit wounds" becomes marginalized.
I particularly enjoyed the articles in the last IWBA that discussed the studies on reaction times to a threat and reactions times relative to a string of fire and cessation of a threat.
Thanks again.
Considering how many of the questions and beliefs expressed during this thread are addressed in depth in the very IWBA documents posted by the OP, I can't help wondering how many people did actually read any of them before posting. There's a wealth of information in them, I downloaded them all and I've spent the better part of my Saturday reading them since. Fascinating and informative, to say the least.
Correct. The force applied to a target is equal to the amount of momentum dissipated in the target over the amount of time it acted on the target.
Force = Projectile Momentum Loss/Time
It is also equal to the amount of energy dissipated in a the target over the distance it penetrated into the target.
Force = Projectile Energy Loss/Penetration Distance
Assuming a bullet stops in the target medium, the force applied to the target is generally easier to calculate with energy than momentum because it's easier to measure the penetration distance than it is to measure the amount of time elapsed between the bullet impact and the time it finally came to a stop in the target medium.
wally
Member
I don't know, when watching high speed video of bullet impacts I'm always surprised by how "long" it takes for the target to react.
Fluid Dynamics has a parameter called the Debra Number which is the ratio of the time constant of the process to the time constant of the observation. Rock strata look solid, but over geological time scales they flow much like a Newtonian fluid.
denton
Member
Taking the energy approach is problematic. When a bullet strikes flesh and bone, or ballistic gelatin, the energy divides itself. Some goes into crushing the target in front of it, some goes into deforming the bullet, and some goes into elastic stretching of the tissue, which snaps back after the bullet passes. Total energy is conserved, but kinetic energy is not. Since kinetic energy is not conserved, and you generally don't know how much energy went where, I don't know how you could make the calculation you suggest.
Dumb old momentum just keeps on being conserved. Total momentum before the collision = total momentum after the collision.
JeffG
Member
...and that, from a very practical standpoint is why you shoot until the threat is down. Just saying...
The calculation is straightforward, interpreting it properly is important. There is no requirement for kinetic energy to be conserved to understand the amount of force applied to a target medium by a given amount of kinetic energy dissipated over a given distance--you just have to understand it's not all acting in the same direction. But if you want to find out how much the target is going to move as a result of the impact then you do need to work with momentum.
denton
Member
Hmmmmm..... I guess you and I have to amicably disagree.
It would be nice if we could have momentum, force, or kinetic energy as a function of time or of distance, but that information is hard to come by.
Since kinetic energy is not conserved, you don't know how much of it you have at any point in the wound channel. How are you then going to set up the equations?
Elkins45
Member
And this would be relevant if animal guts were made of steel plate. How a steel plate and a game animal behave are entirely different things. Once a bullet passes out the other side of an animal it ceases to have any effect.
I've shot plenty of deer with my Savage smokeless muzzleloader over the last 15 years, all with a 300 grain bullet moving at over 2000fps. That's heap big momentum in a 45 caliber bullet. The other 50% of my deer kills have been with a variety of modern small bore rifles, usually a 270 or 257 Weatherby.
The deer shot with the big, heavy bullet all run a few yards before they drop. The deer shot with the fast movers usually DRT or run a significantly shorter way. This thread is in the rifle section, so let's assume it's about rifles. All of my evidence is that fast bullets are quicker killers.
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You always know how much kinetic energy you have--it's easily calculated from the projectile velocity.
You made this statement earlier:"The force, and hence the pressure, a bullet applies to the target is equal to the rate at which the bullet is shedding momentum."
The rate of change (with respect to time) of momentum relates force and momentum as a function of time.
In exactly the same way, the force a bullet applies to the target is equal to the rate of change (with respect to distance) that the bullet is shedding energy.
I think somehow we're talking past each other...
denton
Member
LOL.... well, possibly.
I'm well aware of the difference between integrating or differentiating with respect to time or to distance. And, all other factors equal, I find it easier to think it terms of energy than momentum.
But, given that, when the bullet is moving through tissue, it is shedding energy by being deformed. It is also shedding energy inflating the temporary wound cavity. There is no convenient way to know how much energy is applied to those tasks and how much is used applying force to the tissue ahead. Since I don't think there is any really good way of modeling those energy diversions, I don't think your proposed model will work.
You can model how much Work it takes to stop the bullet, [integral] F(x) dx, and that's equal to the change in KE. But not all that Work comes from the force couple at the bullet-tissue interface. And that's the rub.
The wound ballistics studies I've seen are based on momentum. The IWBA reports posted for us, Jan 92, P13 show one line of reasoning for momentum based wound models.
Whatever or disagreement on the facts, it's a pleasant conversation. Thank you.
I suppose those are somewhat natural assumptions, but, to be clear, I'm not arguing either of those propositions unless you believe that force applied to the target is equivalent to stopping power.
For one thing, I'm not entirely sure that "stopping power" is even an actual quantity. I think it's more of an idea of what people imagine bullets should do more (or what they want them to do) than it is a measureable quantity.
Even if I were to accept that it is actually something that can be scientifically characterized, for the sake of argument, I don't believe it can be quantified with a single number. Not velocity, not mass, not energy, not momentum, not some heuristic number, not TKO figures, not diameter, and not any mathematical combination of any of those values.
It seems to me that those are needless complications. The bullet isn't rubbing up against the sides of the wound channel and physically pushing them out of the way, the sides are "splashed" out of the way by the application of force straight ahead. And the force that deforms the bullet is applied to the bullet due to an equal and opposite force applied straight ahead against the target medium. So while not all the energy applied by the bullet moving forward is going to result in the target moving in the direction of the bullet, it is still force applied to the target medium and it is still force that (however it is divided/directed) resulted from a rate of change of projectile energy with respect to the distance it moves forward.
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Officers'Wife
Member
All of this is beyond my pay grade but the source data is interesting. As another poster - I had a grandfather that spoke of John Browning much the same way a priest talks of Mother Mary, John Garand and Julian Hatcher were apostles and Sandy Hook Proving Ground is the Promised Land. His theory on the subject that the whole idea was (and I quote) "to let in a lot of air and let out a lot of blood." In his view either the 30-06 or the 223 were most likely to pass through the target. The diff (again, according to him...) a 223 will be deflected by bone and exit at an angle, the 30-06 will shatter bone and go straight through. Whether he was right or wrong I have no idea but he had been far closer to the subject that I so I tend to give his opinion far more weight than bowling pins, steel plates or ballistic gelatin.
One of my grandfather's "war stories" had to do with the confusion surrounding the evacuation from Chosin Reservoir. To make a long story short, a Chinese officer tried to shoot my grandfather and missed. My grandfather got off a hurried, essentially unaimed shot in return. Both dove for cover and over the next few minutes crawled around, trying to stay under cover while looking for a shot and exchanging three or four more rounds; all of which hit some obstruction. The men with my grandfather finished off the Chinese soldiers that were with the officer and came looking for my grandfather. When they found him, they also found the Chinese officer dead. My grandfather's unaimed shot had hit the Chinese officer in the leg and he had bled to death.
Real world confirmation of what you were saying.
230 gr at 880 fps (395 ft lbs) has the same momentum as 55 gr at 3680 fps (1654 ft lbs).
300 gr at 1200 fps (959 ft lbs) has the same momentum as 100 gr at 3600 fps (2877 ft lbs).
But the effects won't be too similar. Momentum and frontal area can be used to approximate penetration of low-velocity projectiles in gelatin, but I don't think looking at momentum alone will make it easier to understand terminal ballistics as a whole.
"Brass Fetcher" uses high-speed video to attempt to measure kinetic energy transfer vs penetration depth, which is interesting, but not an ultimate measure of effectiveness.
According to Dr. Gary Roberts, "DocGKR", these two loads gave similar penetration in testing and the momentum isn't too different (47 vs 42 lb ft/s). Kinetic energy is 1628 ft lbs for the .30-30 and 855 ft lbs for the .44.
.30-30 Win 150 gr JSP Silvertip (X30302), bare gelatin: velocity=2211 f/s, penetration=18.9”, averaged recovered diameter=0.57”, recovered weight=125.8 gr [16" Winchester 94]
.44 Magnum Cor-Bon 225 gr XPB (DPX44M225/20), bare gelatin: velocity=1308 f/s, penetration=19.3", averaged recovered diameter=0.70", recovered weight=225.2 gr [5" S&W 629]
Yeah.
Not surprising at all.
The spinal column is about an inch-and-a-half to two inches wide running more or less down the center of the body. But most of that width is bone and cartilage. The nerve bundle that must be reached - and severed - by the bullet in order to be effective is only a fraction of an inch in diameter which greatly diminishes the likelihood of a hit.
And when approached from the front, the vertebrae are roughly triangular in shape and are likely to deflect a bullet or - since the bullet will be moving very slowly by this point - fully absorb the energy of the bullet in breaking the bone.
someguy2800
Member
My experience has been the opposite. I tried going light and fast in my 25-05 with a few different 100 grain bullets pushed as fast as I could make them go and the results with all three were disappointing even with almost all of them being double lung and heart shots. I've had much better results with 120 grain bullets at a more moderate velocity, as well as observed many other deer shot with 270's with 150's, 30-06's, 30-30's ect... I have been taking notes for about 10 years on all the deer shot in our group. I observe the organs taken out to see what was destroyed by the shot and how large the wound channel is and the size of the blood trail. In my observations of about 100 deer the heaviest bullet seams to win given the same shot placement.
Before we started monkeying around with it, the original 55 grain cannelured FMJ bullet for the 223 was supposed to come apart at the cannelure shortly after entering the target and thus produce two wound channels; one of which might or might not increase the severity of the injury by striking bone.
I followed this line of reasoning when I developed a load for use in my 18 inch 1:12 Mini-14 by selecting a heavier (and thus longer and more difficult to stabilize) 60 grain bullet. And while I have yet to employ the round at longer distances than about 100 yards (where the effect would presumably occur), the fact I get round entrance wounds and keyhole exit wounds suggest I may be close.
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