JohnRich 4 #1 October 9, 2003 Here is something which Dropzone.com readers may find interesting. This write-up comes from something I did several years ago, which I discussed on an aviation forum at the time. I'm posting it here for skydivers to read, enjoy and comment upon. Every July 4th and New Year's Eve, the subject of people shooting guns into the air comes up for debate. On such holiday occassions, there is sometimes a news story of someone being killed by "falling bullets", and policemen parking their patrol cars under bridges to avoid the deluge. The discussion surrounding this practice centers around the danger to people who may be hit by descending bullets. There is a great deal of disagreement over the speed of a freefalling bullet and its ability to kill someone. Opinions on freefall speed vary from anywhere between 100 to 400 mph! Some guesses are just "gut instincts" and some were from sophisticated computer ballistics programs. There were also some descriptions from "Hatcher's Notebooks" - Hatcher was an Army officer that did numerous experiments with guns and ammunition. Well, I conducted a personal experiment once, which may shed some direct light on this subject! I am a skydiver with over 4,000 jumps experience, and I'm also an experienced shooter. I combined these two interests in an, admittedly very unscientific, experiment. I wanted to estimate the freefall speeds of various bullets by taking them out of an airplane with me on a skydive, releasing them in freefall, and seeing which direction they went, up or down, relative to my own 120 mph terminal velocity. The four bullets in the experiment, and their weights, were: #1 .22 rimfire, 25 grains #2 .223, 55 grains #3 9mm, 115 grains #4 .45, 230 grains Note: a grain is a unit of weight with 437.5 grains to an ounce. This provided a wide range of weights, sizes and shapes for comparison. As I prepared to exit the plane, I pinched the .22 bullet between the index finger and thumb of my left hand, the .223 likewise in my right hand, the 9mm cupped in the palm of my left hand by the outside three fingers, and finally, the .45 cupped likewise in my right hand. The plan was to release the bullets one at a time, from lightest to heaviest, and observe their freefall velocity. Freefall from 13,500 feet provides 70 seconds of working time, with the first 12 seconds used to accelerate to 120 mph, at which time my freefall acceleration tops-out at 120 mph and increases no further. This would allow a good 10 seconds to observe each bullet in turn as it was released. I spotted myself over the middle of a very large, wide open, uninhabited field, exited the plane and assumed a face-to-earth body position. I waited 12 seconds to reach my terminal velocity of 120 mph, held out my left hand in front of me, and opened up my index finger and thumb and released the .22 25-grain bullet. The bullet rose "up" rapidly relative to my own 120 mph speed. It took only about two seconds for it to disappear out of sight above me. Next I stuck out my right hand into the solid air in front of me (avoiding the low pressure over my back) and released the .223, 55-grain bullet. It too rose "up", but not quite as fast as the .22. Third, I released the 9mm, 115-grain bullet. Likewise, it too rose up and vanished out of sight above me, but took much longer than the first two bullets. It's rise was fairly slow. Finally (I'm really having fun now!) I released the .45, 230-grain bullet. This one stayed with me in perfect synchronization with my 120 mph fall. I actually flew in formation with it for about 20 seconds! It was tumbling end-over-end wildly and the nose and tail were just a blur, while the center appeared solid to my vision. At this point, I tracked horizontally to get out from under these four falling bullets, opened my parachute, and floated back down to the landing area with a big smile on my face, thinking about the interesting results. My conclusion, based upon actual freefall with these projectiles, is: Speed of .22, 25-grain - about 60-80 mph Speed of .223, 55-grain - about 80-100 mph Speed of 9mm, 115-grain - about 100-110 mph Speed of .45, 230-grain - 120 mph There you have it: direct observation evidence. The folks with the ballistic programs had me believing 300 mph, until now. Hatcher concluded a speed of 200 mph for .30 caliber 150 grain bullets, but this was computed based upon math using the initial muzzel velocity and the time it took bullets to return to earth. My experiment is not very scientific, but I believe what I see with my own eyes. One flaw in my test is that I was unable to spin-stabilize the bullets, in the manner in which they would be oriented if fired from a gun. So the terminal velocity of a bullet tumbling end-over-end may be different from that of a bullet which is spin-stabilized in freefall, falling nose or tail first. The Army considers 60-foot-pounds of energy the amount necessary to produce a disabling injury with a bullet. Even using Hatcher's speed of 200 mph, that freefall speed would produce only 30 ft-lbs. So, my conclusion is, contrary to popular myth, that if you are hit by a falling bullet, it will not kill you. More likely, it's just going to sting like hell. This does not apply to shots fired at an angle to produce an arc trajectory, whereby much of the horizontal velocity is retained by the time the bullet reaches the ground again. Despite these conclusions, I am not encouraging anyone to go out and shoot their guns straight up into the air! Comments? Quote Share this post Link to post Share on other sites
AggieDave 6 #2 October 9, 2003 Quote Despite these conclusions, I am not encouraging anyone to go out and shoot their guns straight up into the air! Man, and I just joined the "Celebrating Terrorists AK-47 Air Shooting" club...I guess that's $10 I'll never get to enjoy... --"When I die, may I be surrounded by scattered chrome and burning gasoline." Quote Share this post Link to post Share on other sites
champu 1 #3 October 10, 2003 if the bullets were tumbling end over end as oppsed to spinning along the axis of travel as they would be if they had been fired wouldn't this instability effect their velocity? Quote Share this post Link to post Share on other sites
Hooknswoop 19 #4 October 10, 2003 Quote if the bullets were tumbling end over end as oppsed to spinning along the axis of travel as they would be if they had been fired wouldn't this instability effect their velocity? I don't think so, because once they reach 'perigee' or even before, they will lose their spinning momentum and begin to tumble. I think it was an accurate test. Derek Quote Share this post Link to post Share on other sites
Fast 0 #5 October 10, 2003 I would think that by the time the bullets reached a speed at which they would start to fall back down, the momentum of the rifling would have stoped. The other thing is that there is probally some disfiguration due to firing, which the test bullets didn't have, which would make them more ball shaped and they wouldn't tumble as much.~D Where troubles melt like lemon drops Away above the chimney tops That's where you'll find me. Swooping is taking one last poke at the bear before escaping it's cave - davelepka Quote Share this post Link to post Share on other sites
masher 1 #6 October 10, 2003 Not that I have much experience shooting, but wouldn't most distortion hapen to the round on impact with its target? If the round is distorted due to firing, then it's going to be pretty inaccurate...-- Arching is overrated - Marlies Quote Share this post Link to post Share on other sites
mnischalke 0 #7 October 10, 2003 The only distortion to a bullet is made by the rifling in the barrel. To distort the bullet, even a lead-based bullet, the pressures would need to be several times greater than standard pressure of the cartridge, such as when a cartridge is fired with a bullet already in the barrel. This would also cause a catistrophic failure to most firearms. A bullet also looses velocity almost instantly after leaving the barrel. "Wind" resistance constantly reduces the speed of a fired bullet. That speed reduction can be slightly increased by gravity, but not much. I think the second phase of this experiment should be done with lead balls, which would reduce the turbulence and tumbling involved with a shaped bullet. Ogive on a VLD bullet causes the bullet to be more efficient than say the same weight in a bullet thats round, but the ogive is probably detrimental when the bullet tumbles. All said, great experiment! Hatcher was a very cool guy! mike Girls only want boyfriends who have great skills--You know, like nunchuk skills, bow-hunting skills, computer-hacking skills. Quote Share this post Link to post Share on other sites
Zenister 0 #8 October 10, 2003 i have a 9mm round my sister and i "collected" from the hood of her car on the 4th of July. we went to the groc to get more alcohol as we get out and shut the doors we hear a loud "tink" and notice the hood suddenly has a crease...low and behold it also has a dent and a 9mm round in it.. since i doubt the tensile strength of the human skull exceeds that of that hood (which it did penetrate slightly) if that round had been a few feet either way one of us might not be here.... "celebratory fire" should be treated as attempted manslaughter whenever anyone is caught doing it...____________________________________ Those who fail to learn from the past are simply Doomed. Quote Share this post Link to post Share on other sites
LouDiamond 1 #9 October 10, 2003 I have to agree with Zenister. The bullets velocity may not be anywhere near what it was when it was fired from the weapon but a solid object falling at it's terminal velocity is still going to cause damage to whatever it strikes. Be it a penny you toss from the Empire state building or a round fired into the air, it's still coming down and will penetrate a good many things in the environment to include soft tissue and bone."It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
firediver 0 #10 October 10, 2003 as I remember it...it only takes something like 8-10 PSI to break a skull. Either way, if i get tinked with a spent round falling from the sky, the motherf***** that fired it better be able to outrun one moving horizontally... Skydiving isn't scary;...but clowns...CLOWNS are scary! Quote Share this post Link to post Share on other sites
JohnRich 4 #11 October 10, 2003 Quote if the bullets were tumbling end over end as oppsed to spinning along the axis of travel as they would be if they had been fired wouldn't this instability effect their velocity? Yes, I think it definitely does. That's why I referred to it as a "flaw" in my experiment. A tumbling bullet should produce more wind drag than one which is spinning vertically, thereby presenting much less surface area to the wind. This is what I think explains the discrepancy between what Hatcher says and what I observed. Hatcher calculated a rate of fall of 200 mph, while I observed 120 mph. But because my bullets were tumbling, that would explain why they were slower. Quote Share this post Link to post Share on other sites
JohnRich 4 #12 October 10, 2003 Quote once they reach 'perigee' or even before, they will lose their spinning momentum and begin to tumble. This was my initial instinct on the matter, but further research showed that this is apparently not true. Bullets can spin at an incredible rpm rate - several hundred thousand revolutions per minute. While the vertical ascent may be stopped fairly quickly due to gravity and wind drag, the spin is retained. These two events are independent, and don't automatically occur together. So once the bullet reaches apogee, it falls back to earth base-first, or else tips over and falls nose-first - still spinning. Hatcher's experiment for this was done by mounting a machine gun on a raft, and floating out into the middle of a large lake. They would fire the machine gun up into the air, then duck underneath a protective roof for shelter, and time how long it took the bullets to splash down in the lake around them. Some of the bullets hit the tin roof or the wood of the raft, and many of them made an impression indicating that they hit base-first. Others were point-first. None hit sideways. This would indicate that the bullets were still spin-stabilized on their return descent. Quote Share this post Link to post Share on other sites
JohnRich 4 #13 October 10, 2003 Quote there is probally some disfiguration due to firing, which the test bullets didn't have, which would make them more ball shaped and they wouldn't tumble as much. The only disfiguration that occurs to fired bullets are some shallow grooves squished into the sides on the bearing surfaces. The bullets are actually a little larger in diameter than the barrel: for example, a .308 rifle shoots .311 bullets. Under the pressure of firing, the lead is compressed a bit to accomodate the shape of the rifling. You can see this by digging them out of a dirt berm behind a target. I don't think those shallow rifling impressions would make much, if any, difference on the terminal velocity of a bullet. Quote Share this post Link to post Share on other sites
adamT 0 #14 October 10, 2003 the question is would the bullet start to tumble when it reached the peak of its arc and started to return to earth. I don't know either way. I think a bullet oriented tapered side down would be traveling much faster then a tumbling one. I also think getting hit in the top of the head by a small tumbling peice of metal travaling at 120mph would kill you. Quote Share this post Link to post Share on other sites
JohnRich 4 #15 October 10, 2003 Quote I think the second phase of this experiment should be done with lead balls, which would reduce the turbulence and tumbling involved with a shaped bullet. Ogive on a VLD bullet causes the bullet to be more efficient than say the same weight in a bullet thats round, but the ogive is probably detrimental when the bullet tumbles. Agreed. As a matter of fact, I have some .50 caliber lead balls. Maybe I should take them out and give them a try... I wonder what the ballistic coefficient is of a lead ball, vs. a typical round-nose bullet? Hmm, I'll have to crack open the reloading book and look at the ballistic tables. Quote Hatcher was a very cool guy! He definitely had a fun job. One of the things he did was to intentionally try to blow guns up by doing stupid things that a soldier might do in the field, in order to find out how dangerous those acts were. For example, firing a .30-06 cartridge in a .303 rifle. By these experiments, he determined that the WWII Japanese Arisaka rifles had the strongest actions of all. He could fire oversized bullets in them, and rather than blow the gun up, the bullet would just squish down into a long and skinny shape, and exit the barrel normally. The action held together despite the enormous pressure increase. Quote Share this post Link to post Share on other sites
LouDiamond 1 #16 October 10, 2003 While I don't discount the validity of that experiment and it's results. I do know that the early 5.56/223 rounds fired out of M-16A1s had a propensity to tumble in flight and could be seen as such on paper targets set at a distance of 200 m plus. Nor was it uncommon to see entry /exit wounds that did not make sense, ie: entry at shoulder and exit on hip. I also think that the weapons condition has a lot to do with it as well. I have run many exercises with foreign Armies and their often worn out weapons. It is not unusual to see full profiles of a bullets shape in the target or in the surrounding trees/structures. Regardless of which end strikes first, it is still going to do damage, even more so if it is tumbling."It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
JohnRich 4 #17 October 10, 2003 Quote we hear a loud "tink" and notice the hood suddenly has a crease...low and behold it also has a dent and a 9mm round in it. But did the bullet impact straight down, or at an angle? If it travelled in an arc through the sky, it would retain much more velocity, than a bullet which freefalls back to earth, having expended all of it's muzzle velocity straight up. Since you didn't indicate that you heard the round being fired, that would tend to suggest that it was fired from some distance away, and thus was not a vertically-oriented shot. So that particular shot may have had more retained energy than the straight-up firings were discussing. To provide some perspective, consider that a pro baseball pitcher can throw a baseball at a top speed of about 100 mph. When a batter is hit with a pitched ball, it hurts like hell, and he usually charges the pitcher to attack him, so that the pitcher doesn't get away with intimidating batters in that manner. But a baseball weighs a lot more than a bullet. That 9mm bullet weighs only one-quarter of an ounce. But it freefalls at about the same speed as a baseball. So if you were to have that baseball pitcher throw a 9mm bullet at someone standing right in front of them, it would certainly sting like hell, but wouldn't do much damage beyond a welt or a bruise. I certainly don't think it would penetrate a skull. Nevertheless, you are correct that firing guns into the air is a dangerous and stupid thing to do, at any angle. None of this discussion should be construed to imply otherwise. Quote Share this post Link to post Share on other sites
JohnRich 4 #18 October 10, 2003 Quote The bullets velocity may not be anywhere near what it was when it was fired from the weapon but a solid object falling at it's terminal velocity is still going to cause damage to whatever it strikes. Be it a penny you toss from the Empire state building or a round fired into the air, it's still coming down and will penetrate a good many things in the environment to include soft tissue and bone. You don't buy that old myth about a penny thrown from the Empire State Building, do you? Do you think such a penny would penetrate the skull of a pedestrian down below on the sidewalk? Quote Share this post Link to post Share on other sites
JohnRich 4 #19 October 10, 2003 Quote I also think getting hit in the top of the head by a small tumbling peice of metal travaling at 120mph would kill you. That is contrary to the wound ballistics studies done by the Army, for the energy produced by lead bullets in freefall, as determined by Hatcher. Quote Share this post Link to post Share on other sites
adamT 0 #20 October 10, 2003 Yeah, im just speculating. Were the tests all done with #s or did they use cadavers? Quote Share this post Link to post Share on other sites
JohnRich 4 #21 October 10, 2003 Quote early 5.56/223 rounds fired out of M-16A1s had a propensity to tumble in flight... the weapons condition has a lot to do with it as well... This shouldn't happen if the proper bullet is used in the proper barrel, in good condition. Firing heavy bullets in barrels with slow rifling twist rates, produces instability. Worn out rifling that doesn't grip the bullet properly also does the same thing. But those are abnormal conditions. Quote Nor was it uncommon to see entry /exit wounds that did not make sense, ie: entry at shoulder and exit on hip. That doesn't have to do with bullet tumbling in flight though. Since bullets are pointed in front, the center of balance is to the rear, since that is where most of the mass lies. That's why they have to be spun to stabilize them in flight. This natural condition due to their shape can cause them to tumble as soon as they strike something. Just like thumping a spinning gyroscope will cause it to wobble. And contact with bone will cause deflections, just like tree branches in a hunting scenario. Quote Regardless of which end strikes first, it is still going to do damage, even more so if it is tumbling. Damage, yes. What's in question is, how much? I think it would likely be just a bruise, or lightly broken skin, but with no penetration or bone fractures. Quote Share this post Link to post Share on other sites
LouDiamond 1 #22 October 10, 2003 Quote You don't buy that old myth about a penny thrown from the Empire State Building, do you? Do you think such a penny would penetrate the skull of a pedestrian down below on the sidewalk? I tell you what. Lets try it, you stand on the sidewalk and I'll pitch the penny A baseball has a larger surface area than a bullet and will cause more blunt trauma than a bullet. The bullet however has a smaller surface area(pinpoint) striking the object ,however the forces that are transfered are magnitudes higher than that of a baseball. A rather unscientific way to look at this is to compare getting hit with a bullet/baseball while wearing a bullet resistant vest and then compare the forces. Am I to understand you correctly where your going with this? You think that getting hit with a falling bullet poses no bodily harm/threat?"It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
JohnRich 4 #23 October 10, 2003 Quote Were the tests all done with #s or did they use cadavers? There have been Army studies of wound ballistics using live animals. Thousands of them. Yech. That's where those wound energy numbers come from. You can readily calculate the energy, in foot-pounds, of a fired bullet using the factors of mass and velocity. And then compare that to the results of those wound studies. I'm sure today's animal rights activists would have a fit over those studies... Quote Share this post Link to post Share on other sites
JohnRich 4 #24 October 10, 2003 Quote Quote You don't buy that old myth about a penny thrown from the Empire State Building, do you? Do you think such a penny would penetrate the skull of a pedestrian down below on the sidewalk? Quote I tell you what. Lets try it, you stand on the sidewalk and I'll pitch the penny I notice that you didn't answer the question. Would you like to try again? Quote Am I to understand you correctly where your going with this? You think that getting hit with a falling bullet poses no bodily harm/threat? I never said "no" threat. I'm just providing info which is contrary to the common belief that freefalling bullets will kill. I wasn't sure myself, until I judged the speed of freefalling bullets with my own eyes, in my described experiment. And as I've said elsewhere, despite this information, I'm not trying to make light of the act of shooting into the air. I'm just trying to provide some facts. Quote Share this post Link to post Share on other sites
LouDiamond 1 #25 October 10, 2003 Quote I notice that you didn't answer the question. Would you like to try again? I believe that if something is dropped, be it from a structure or from a gun and is allowed to fall, even at it's terminal velocity that it has the posibility of killing you. Granted the objects mass comes into play but we are talking about bullets here and not feathers. And yes, I believe that if you were struck with a penny thrown from the Empire state building that it could posibly end in death or bodily damage. Here is a novel idea and new experiment for you to try if you are so inclined. Have a friend drop various caliber bullets from a height of lets say 10 feet to start onto your head and then progressively work up to say 1 story if your still able to. This is keeping in mind that the object that is striking you still hasn't reached it's terminal velocity yet. If your body is not penetrated by the object, the blunt trauma alone could be enough to kill as well. In thinking about this I think a good study to look at would be those done by NASA on the debris in space and how things as minute as a grain of sand can have on inanimate materials."It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
