Mythbusters: Gun Myths

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Taking the lead from another thread, it seems that the Mythbusters boys do a fair amount of firearm based myths.

The best one I saw was when they shot into a pool to see if it really was safer to duck under water in a fire fight.

They shot a .50 cal into the water and it didn't even hit the ballistics gel which was, I believe, 3 feet away. The only caliber that didn't sink to the bottom of the pool was .308!

So that myth was confirmed. Most bullets only traveled a short distance before losing momentum. I believe they said you'd be safe in about 2 feet of water.


What myths did you see get busted or confirmed?
 
SiameseRat said:
They shot a .50 cal into the water and it didn't even hit the ballistics gel which was, I believe, 3 feet away. The only caliber that didn't sink to the bottom of the pool was .308!

So that myth was confirmed. Most bullets only traveled a short distance before losing momentum. I believe they said you'd be safe in about 2 feet of water.

Wow.. does anyone else find this totally amazing? Did they compare hollow points to FMJ? I guess I'd wonder if the hollow points expanded in the water... That sounds like a good one to see.

I saw one where they simulated someone stopping a bullet in their teeth. It wasn't that exciting. Another one they tried to "blow up" somekind of air tank stuck inside a shark- like the 'Jaws' show. Not much to see.
 
SiameseRat said:
So that myth was confirmed. Most bullets only traveled a short distance before losing momentum. I believe they said you'd be safe in about 2 feet of water.

The did use FMJ, and it just disintegrated. That was a great one. I always suspected that. Its funny, after I saw that show the very next day I was at the range with my wife and there was this older guy teaching 2 teenagers how to shoot a few bolt action rifles. He was telling stories of killing bears and random exaggerated hunter stuff. But he did say "Sharks are now conditioned to the smell of gun powder." from what being shot at? and their sense of smell? We just smiled.

Anyways I really liked the one when they shot the dummy to show that bodies don't go flying 10 feet. That's always been a nasty myth in movies. You get shot, you fall down.
 
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The angle had a lot to do with it too. If it was shot at 90 degrees to the water, it went deeper...natcherrly..becasue with an angled shot it has to go along botha horizontal plane AND a vertical plane. So you have a better chance of 'dodging' the bullet if you are being shot at from the shore than if a boat was directly over you shooting straight down.

The slower the bullet the further it went in the water. Sorta like bigger and slower is better in the .45 vs others.

Drive a fast light modern car (equates to a high speed light rifle bullet) into a wall see what happens. Drive a slow moving heavy bulldozer into a wall (equates to a .45). The results are slightly different.

I wasn't really surprised by the results of the show.
 
C-pher said:
They did one that had to do with a squib.

They shoved a bullet into the end of the barrel. I didn't like it because a squib would be closer to the breach. So, it had enough distance to shoot out the hammered in head.

Not always. We had a really weird one at the Jim Conway class at Westford a couple of months back. The bullet was actually sticking half way out of the muzzle of the gun. We tried absolutely everything we could to pull it the rest of the way out, but finally had to give up and tap it back through the barrel and out the breech end. Definitely the exception to the rule, though.

Ken
 
did anyone see the episode where they submerged different firearms to see if they could be fired while underwater and be lethal.i believe the myth was that you could but they found out that lethal range was only 2 ft.
 
you forgot the one where they fired both pistol and rifle straight up to see if the returning bullet was lethal according to the depth of penetration in desert soil non fatal. rifle was M1 garrand and pistol was a sig 226 I believe
 
When a bullet is shot in a steep arc or straight up, then falls to earth there are a couple of differences from the ballistics we normally consider. First, and most important, the vertical component of the velocity decreases to zero at the top, then increases only to the extent that gravity and air resistance affect it. IIRC, both Hatcher's experiments and standard ballistic calculations indicate that the maximum downward velocity will never be more than 200-300fps, regardless of muzzle velocity. As a result, the threat posed by a bullet fired into the air will depend primarily on whatever horizontal velocity it retains, rather than on its total muzzle velocity. The second difference, which contributes to the low final velocity, is the fact that the spin of the bullet tends to keep it in its original orientation, falling base first.

Ken
 
Pilgrim said:
The angle had a lot to do with it too. If it was shot at 90 degrees to the water, it went deeper...natcherrly..becasue with an angled shot it has to go along botha horizontal plane AND a vertical plane. So you have a better chance of 'dodging' the bullet if you are being shot at from the shore than if a boat was directly over you shooting straight down.

The slower the bullet the further it went in the water. Sorta like bigger and slower is better in the .45 vs others.

Drive a fast light modern car (equates to a high speed light rifle bullet) into a wall see what happens. Drive a slow moving heavy bulldozer into a wall (equates to a .45). The results are slightly different.

I wasn't really surprised by the results of the show.

When I was a little boy, my father would tell me of his experiences in WWII. He was UDT, and went into action wearing a bathing suit, a pair of sneakers, and a lot of C-3. I remember once, with the bedcovers pulled up to my chin, as he said goodnight, he told me that Japanese machinegun bullets would burn out their velocity at about two feet of depth, and that you could actually catch them in your hand if you were a bit lower than that (2 1/2 feet, if I remember correctly). Of course, he was talking about batteries firing from the shoreline at targets (i.e., he and his compadres) at various ranges, and at a dowward angle comparable to what the Mythbusters experimented with at the pool.

So, that show rediscovered something that my dad knew from experience. Maybe they shoud have asked a UDT vet.
 
and how much fun would that be for adam and jamie on these subjects they REALLY get carried away as in last night a steam powered howitzer maybe on this afternoon
 
KMaurer said:
When a bullet is shot in a steep arc or straight up, then falls to earth there are a couple of differences from the ballistics we normally consider. First, and most important, the vertical component of the velocity decreases to zero at the top, then increases only to the extent that gravity and air resistance affect it. IIRC, both Hatcher's experiments and standard ballistic calculations indicate that the maximum downward velocity will never be more than 200-300fps, regardless of muzzle velocity. As a result, the threat posed by a bullet fired into the air will depend primarily on whatever horizontal velocity it retains, rather than on its total muzzle velocity. The second difference, which contributes to the low final velocity, is the fact that the spin of the bullet tends to keep it in its original orientation, falling base first.

Ken

A couple of refinements on this analysis, which is pretty close to the mark.

Yes, the vertical upward velocity decays to zero, and that is why muzzle velocity is irrelevant. Assuming a round is fired at a very high angle (say, greater than 75-80 degrees), its horizontal velocity will also quickly decay to nearly zero, though for other reasons. As a result, the energy of the now falling slug is solely based on its mass and terminal velocity.

A falling object subject to the pull of gravity is subject to a constant force tending to cause it to increase its velocity at the rate of 32 feet per second per second. However, if the falling object is falling in a medium of greater than zero density, such as air, it is also subject to an opposite force, parasitic drag, which increases more than linearly with velocity. What happens is that the falling object increases in velocity until the force of the parasitic drag exactly equals the force of gravity, at which point its velocity stops increasing and becomes fixed. This is the object's terminal velocity.

Parasitic drag, in turn, is a function of (among other things) the cross section of the falling object. A spire point falling point first has a lower cross section than the same slug falling more or less horizontally, and the latter therefore has a lower terminal velocity.

Most rifle slugs in free fall after exhausting ballistic energy do tend to fall somethere askew between base down and horizontal -- and not nose down -- but this has nothing to do with rotational spin. Rather, it has to do with the center of gravity (or center of mass) of a monolithic object of a rifle bullet's shape: there is simply more mass in the hind end.

There are empiracal studies measuring the terminal velocity of common (30-40 years ago) rifle bullets in free fall. I don't remember the specifics, but I seem to recall that terminal velocity was a good bit less than 200-300 fps (which would be 136-204 mph).
 
Producer said:
The did use FMJ, and it just disintegrated. That was a great one. I always suspected that. Its funny, after I saw that show the very next day I was at the range with my wife and there was this older guy teaching 2 teenagers how to shoot a few bolt action rifles. He was telling stories of killing bears and random exaggerated hunter stuff. But he did say "Sharks are now conditioned to the smell of gun powder." from what being shot at? and their sense of smell? We just smiled.

Anyways I really liked the one when they shot the dummy to show that bodies don't go flying 10 feet. That's always been a nasty myth in movies. You get shot, you fall down.


Hey Producer, I surely don't think a shark can be conditioned to the smell of powder but I do know for a fact that some Abalone divers in Ca carry Glocks but they are used as a contact weapon. Like a bang stick they are used not for the bullet but for the concussion. Most of the bang stick companies actually reccommend that you use blanks. Using a handgun allows for multiple shots unlike a bangstick which is pretty much a single shot and then you are fish food.
 
jshooter said:
Hey Producer, I surely don't think a shark can be conditioned to the smell of powder but I do know for a fact that some Abalone divers in Ca carry Glocks but they are used as a contact weapon. Like a bang stick they are used not for the bullet but for the concussion. Most of the bang stick companies actually reccommend that you use blanks. Using a handgun allows for multiple shots unlike a bangstick which is pretty much a single shot and then you are fish food.

That's pretty cool. I still find it hard to believe a whole species would be conditioned. But, maybe gunpowder is a good shark repellent.
 
RKG said:
A couple of refinements on this analysis, which is pretty close to the mark.

Yes, the vertical upward velocity decays to zero, and that is why muzzle velocity is irrelevant. Assuming a round is fired at a very high angle (say, greater than 75-80 degrees), its horizontal velocity will also quickly decay to nearly zero, though for other reasons. As a result, the energy of the now falling slug is solely based on its mass and terminal velocity.

A falling object subject to the pull of gravity is subject to a constant force tending to cause it to increase its velocity at the rate of 32 feet per second per second. However, if the falling object is falling in a medium of greater than zero density, such as air, it is also subject to an opposite force, parasitic drag, which increases more than linearly with velocity. What happens is that the falling object increases in velocity until the force of the parasitic drag exactly equals the force of gravity, at which point its velocity stops increasing and becomes fixed. This is the object's terminal velocity.

Parasitic drag, in turn, is a function of (among other things) the cross section of the falling object. A spire point falling point first has a lower cross section than the same slug falling more or less horizontally, and the latter therefore has a lower terminal velocity.

Most rifle slugs in free fall after exhausting ballistic energy do tend to fall somethere askew between base down and horizontal -- and not nose down -- but this has nothing to do with rotational spin. Rather, it has to do with the center of gravity (or center of mass) of a monolithic object of a rifle bullet's shape: there is simply more mass in the hind end.

There are empiracal studies measuring the terminal velocity of common (30-40 years ago) rifle bullets in free fall. I don't remember the specifics, but I seem to recall that terminal velocity was a good bit less than 200-300 fps (which would be 136-204 mph).

Nice explaination/description.

Here's my conclusion- if you were unfortanate to get hit by one of these falling pieces of lead... it would still hurt like a son of a gun!
 
No doubt it would smart. And, if it hit you just the right way, it might kill. But, then, walking into a partially open door and hitting your nose just the right way could also kill. It's a hard world.
 
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