How far will it go??

You guys are not telling the entire story of General Hatcher's tests and conclusions.

He said that a 30 caliber, 150 grain military bullet fired straight up would return to earth base first at a velocity of about 300 fps. That will generate an average of 3o fp of energy, not enough to produce a disabling wound.

He went on to say that the result would be entirely different as the weight of the bullet increased or decreased. And different as the angle of trajectory changed.

There are known examples of people being killed by falling bullets, but the circumnstances are completely different than those of Hatcher's tests.

Ray
 
Are y'all sayin' that the "drag" both up and down knocks off ~700 fps of an originally fired 1000 fps bullet?
 
Wilbur

I think it's a case of the drag (gravity) going up, knocks off all of the original 1000 fps velocity. Coming down, the pull of gravity accellerates the bullet from zero to x fps. A falling object tends to balance its weight against the air resistance at a certain velocity. In the case of a 30 caliber, 150 grain bullet, that point is approx 300 fps.

Even though a falling bullet is still spinning quite rapidly, there is no side pressure to cause it to turn point down so it will hit the earth base first. At some angle less than 90 degrees, the pressure will cause a bullet to turn and follow it's own trajectory. Otherwise, howitzer projectiles, fired at very high angles , would not work.

Ray
 
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Cheechako said:
He said that a 30 caliber, 150 grain military bullet fired straight up would return to earth base first at a velocity of about 300 fps. That will generate an average of 3o fp of energy, not enough to produce a disabling wound.

There are known examples of people being killed by falling bullets, but the circumnstances are completely different than those of Hatcher's tests.

Ray
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Ray, you're the second person to assert those bullets could not kill someone. Now I don't have any dead people to show off, but if they do indeed fall at 300fps, that is way enough to penetrate a skull in my opinion. All I have to go by is chrony'd balls at ~250fps and the damage they did. My "Backstop" was 3' past the chrony, so pretty much lost no velocity. I could not believe you could shoot through commercial carpet with just a primer and a 2" barrel. Now, I'm talking about a hit in the head, but if a bullet could not kill ya just falling, I'd be surprised.
 
4mesh

I'm not asserting anything. I'm simply saying that this is what Gen Hatcher concluded. As an Army officer, his conclusions are based on and supported by extensive testing of terminal ballistics in both live animals and human cadavers. That has to be worth something, IMHO.

Ray
 
Out of curiosity, I googled BB guns and paint ball guns. The lower powered BB guns usually fire the BB at 300 fps +/-. Paint ball gun manufacturers recommend that the user regulate them to fire at 300 fps. Coincidence??

Ray
 
I was thinkin' going up the bullet decelerates at 32ft/sec/sec plus drag - which means that if it suddenly found itself at peak in a vacuum it couldn't reach 1000 fps on the way back down. On the way down it accelerates at 32ft/sec/sec minus drag slowing it down even more. If the result is 300 fps then drag accounted for 700 fps. But that's not all there is so I now realize. Given an extra mile to fall, what you're sayin' is that it wouldn't go faster because somewhere around 300 fps the drag equals the force of gravity and it stays right there for the duration...???...

Further, if you shot a bullet straight down over a hypothetical infinite distance in atmosphere it would reach 300 fps and remain there. Cool!
 
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That's what the laws of physics say. And Gen Hatcher.

What do I say?? I'm still trying to figure out how electricity works.:cool:

Ray
 
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Know your target. I've heard that some bullets change shape after they hit a hard surface. Ricochets have been known to fly like a Frisbee, so no telling where it might land.
 
I'm with 4mesh on this one for a change, Would you like to get hit in the head with 175 gn. bullet out of a slingshot. I know they aren't going 300 fps and I've killed a lot of rabbits when I was a kid with steal balls a lot smaller. So please don't be shooting straight up in the air to find out!

Joe Salt
 
The mythbusters did a show on this very subject several years ago. They fired 30-06's, 9mm, and 45 acp's straight up from a salt flat or dried lake bed in the Mojave desert. Most of the bullets that were found barely went 1/4" into the sun baked mud. The 9mm's were especially shallow. From these tests, they all agreed that it would be pretty hard to kill anyone in this manner. However, they did mention some other tests that the military did that had slightly different results. They also ran the math and found that if there was even just a slight deviation off 90 degree (straight up) trajectory, the bullets all had enough of an arc to easily kill. To this date, this topic was the only one that received both a "busted", "plausible", and "confirmed" rating all at the same time.


http://mythbustersresults.com/episode50
 
taken from Goodgroupers link
In the case of a bullet fired at a precisely vertical angle (something extremely difficult for a human being to duplicate), the bullet would tumble, lose its spin, and fall at a much slower speed due to terminal velocity and is therefore rendered less than lethal on impact. However, if a bullet is fired upward at a non-vertical angle (a far more probable possibility), it will maintain its spin and will reach a high enough speed to be lethal on impact. Because of this potentiality, firing a gun into the air is illegal in most states, and even in the states that it is legal, it is not recommended by the police. Also the MythBusters were able to identify two people who had been injured by falling bullets, one of them fatally injured. To date, this is the only myth to receive all three ratings at the same time.
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I don't know what probabilities are on this. Maybe this above is clouded or false, but I'd tend to believe it is possible.

Ray, on the 300fps recommended limits above, that is MV. They loose velocity very quickly. This 3xx fps we're talking about is the actual velocity as if those paintballs or bb's were fired at point blank. Very different animals. I have been shot many times by Airsoft rifles. These are .2gram projectiles (3.1grains) and at 20 meters, on full auto every hit draws blood if it hits your skin. We wear full face gear, ear protection, scarves, but in heat, you let your arms out. And do they hurt! These are plastic projectiles 6mm diameter, and they shed velocity like a parachute. Still, fired from a 400fps mv weapon, we have rules not to fire upon anyone at <10m. It's just not worth the risk to us.

I realize, all the proof here is hypothetical, hearsay, or just plain conjecture. I'm gonna stick with my original thoughts on it anyway.

About the only thing that makes me want to change sides and say now it can't happen, is that Joe agreed with me above! :D
 
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Wilbur look up terminal velocity. You can find the formulas and also some fun facts while your at it.
 
I doubt if Mythbusters can show any evidence to back up the statement, "the bullet would tumble, lose its spin, and fall at a much slower speed. . ." I can't speak directly to small caliber bullets but I know that artillery projectiles do not tumble nor do they lose their spin when the reach the top of their vertical. They continue to spin and fall back to earth in a base down position, still spinning when they hit. I was a USN Gunners Mate and often went to a firing range on a beach (in MD as I remember) where the Navy did experiments such as vertical firing. We saw examples of artillery projectiles still buried base first in the sand proving that they did not tumble or nose over except at angles less than approx 85 degrees. There is no reason for a bullet to behave any different. Hatcher said, ". . . When the bullet reaches the top of its flight, then stops and starts back, it is still spinning, and if it is stable and well balanced, it will come down base first. . ." The premise of Mythbusters is that things aren't always as they seem to be, or should be, and they sometimes fall into the trap of assuming things that really aren't true. That statement about bullets losing spin and tumbling is one example.

Ray
 
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Cheechako said:
I doubt if Mythbusters can show any evidence to back up the statement, "the bullet would tumble, lose its spin, and fall at a much slower speed. . ." I can't speak directly to small caliber bullets but I know that artillery projectiles do not tumble nor do they lose their spin when the reach the top of their vertical. They continue to spin and fall back to earth in a base down position, still spinning when they hit. I was a USN Gunners Mate and often went to a firing range on a beach (in MD as I remember) where the Navy did experiments such as vertical firing. We saw examples of artillery projectiles still buried base first in the sand proving that they did not tumble or nose over except at angles less than approx 85 degrees. There is no reason for a bullet to behave any different. Hatcher said, ". . . When the bullet reaches the top of its flight, then stops and starts back, it is still spinning, and if it is stable and well balanced, it will come down base first. . ." The premise of Mythbusters is that things aren't always as they seem to be, or should be, and they sometimes fall into the trap of assuming things that really aren't true. That statement about bullets losing spin and tumbling is one example.

Ray
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Ray,
that paragraph and the sentence you refer to was not written by the mythbusters. It appears to be a Discovery Channel explanation of the show and it didn't really reflect what was actually said on the show with 100% accuracy.

I tried to find the episode on Youtube to post here, but apparently, it's just about the only show they've done that nobody has uploaded yet.:( I did find the one about shooting a 50 cal into a swimming pool though........pretty interesting.
 
There are some things said above that to me are questionable and I've seen them said many times in the past.

There seems to be an accepted idea about bullet spin that I'm not sure I agree with. Folks say a bullet's spin rate does not decay the same as velocity or whatever. Ok, fine, I'd agree as long as it is stable and traveling point first. But, after it becomes unstable, I would contend that the spin rate is converted into energy spinning the bullet off axis, and now that rate decays almost instantly.

Think back to when you were a kid and had a bike. Me, I was fascinated with the idea of centrifugal force and I can still remember taking my bike, sitting it upside down on the handle bars and spinning the front tire. Now, spinning it as fast as it could go, I remember turning the wheel side to side and watching the rotation rate drop like a rock. Now, at age 6 or 7, I didn't know the answer to why this happened, but, it stuck with me for a lifetime. Once that tire is no longer spinning in one plane, the spin rate drops like you hit the brakes... Why?

So, fast forward more years than I care to admit and here we are talking about bullets at 100K rpms or so. I say they act the same way. Once they become unstable and turn off axis, they basically stop spinning. I'm just guessing here, but, if I take a dowelpin, and throw it in such a fashion that it is spun as much as I can spin it, it'll begin spinning on it's center, then, it'll go completely haywire and all that spin goes away and it tumbles. Actually, they usually just throw the ends in big circles, but continue to spin somewhat, just not neatly. Draw a line with a sharpie on the side of a 3" x 1/2" dowel (steel) and throw it up in the air spinning as much as you can. Watch the rate it spins as it goes from spinning gently, to spinning wildly. It'll spin a WHOLE lot less in basically no time at all. Now, if this is not the same effect as a bullet that becomes unstable, then ok, show me the math behind it. But, I say they are similar till proven otherwise. I'm not saying all the spin stops, but, most of it does. I'd say, that amount of spin that is capable of producing significant centrifugal force, goes away. Just like a gyroscope, when it spins gently, it keeps spinning. When it is turned wildly, it looses rpms at a terrific rate.

Are the two situations dissimilar?
 
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4mesh

Read Hatcher's notebook. He says, ". . .and if it is stable and well balanced, it will come down base first. . ." Hatcher did report some bullets falling back to earth sideways and at different angles. Not all bullets are stable and they will tumble, as any long distance shooter knows. On the other hand, not all bullets become unstable, but continue on, pointy end first, to extreme distances. Artillery projectiles are notoriously stable and well balanced. So are .50 BMG bullets.

There are many details of external ballistics that seem to counter what we intuitively think to be facts. I'm sure you know shooters who still hold to some of their old ideas, especially shooters who shoot long range. It took years for some of them to understand that ballistics are nothing but simple science and you cannot bend or break the rules no matter how wrong they appear to be. There's not a month goes by, on this Forum, where some of those old ideas come up, again, and we argue the same old arguements over and over again. This one will not end here, I'm sure.

Ray
 
4Mesh said:
There are some things said above that to me are questionable and I've seen them said many times in the past.

There seems to be an accepted idea about bullet spin that I'm not sure I agree with. Folks say a bullet's spin rate does not decay the same as velocity or whatever. Ok, fine, I'd agree as long as it is stable and traveling point first. But, after it becomes unstable, I would contend that the spin rate is converted into energy spinning the bullet off axis, and now that rate decays almost instantly.

Think back to when you were a kid and had a bike. Me, I was fascinated with the idea of centrifugal force and I can still remember taking my bike, sitting it upside down on the handle bars and spinning the front tire. Now, spinning it as fast as it could go, I remember turning the wheel side to side and watching the rotation rate drop like a rock. Now, at age 6 or 7, I didn't know the answer to why this happened, but, it stuck with me for a lifetime. Once that tire is no longer spinning in one plane, the spin rate drops like you hit the brakes... Why?

So, fast forward more years than I care to admit and here we are talking about bullets at 100K rpms or so. I say they act the same way. Once they become unstable and turn off axis, they basically stop spinning. I'm just guessing here, but, if I take a dowelpin, and throw it in such a fashion that it is spun as much as I can spin it, it'll begin spinning on it's center, then, it'll go completely haywire and all that spin goes away and it tumbles. Actually, they usually just throw the ends in big circles, but continue to spin somewhat, just not neatly. Draw a line with a sharpie on the side of a 3" x 1/2" dowel (steel) and throw it up in the air spinning as much as you can. Watch the rate it spins as it goes from spinning gently, to spinning wildly. It'll spin a WHOLE lot less in basically no time at all. Now, if this is not the same effect as a bullet that becomes unstable, then ok, show me the math behind it. But, I say they are similar till proven otherwise. I'm not saying all the spin stops, but, most of it does. I'd say, that amount of spin that is capable of producing significant centrifugal force, goes away. Just like a gyroscope, when it spins gently, it keeps spinning. When it is turned wildly, it looses rpms at a terrific rate.

Are the two situations dissimilar?
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As I understand it bullets don't tumble as they come back down. They DO tip though. Generally they end up landing 'tilted' or even laying almost flat from precession. Gyroscopic precession based on rate of rotational velocity decay is the reason bullets typically fall with a sideward component. A bullet is spinning much faster than a stick..... like over 200,000rpms......and it takes what 5-8 seconds to run out of upward velocity? It doesn't slow down that much rotationally. Then, as it returns, it's dropping slowly and 'weight forward' so there's no tipover component, but sufficient air pressure to keep it from spinning wildly.



Speaking of translating rotational energy, get one of these. "For the kids" http://www.nsd.com.tw/

they're cool

al
 
IMO the bullets that come down point first and kill people are coming off the end of a parabolic trajectory. They may be coming almost straight down but they still contain residual velocity and are stabile. A bullet fired straight up CAN'T fall point first whereas a bullet fired over a trajectory nearly has to.

al
 
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