AR15.Com Archives
 Why oh why can't we get away from this "tumbling bullet" BS?
BlackDog714  [Team Member]
1/9/2007 11:49:52 PM
Watching "Guns: Machines of War" on the National Geographic Channel and their telling me the reason the M-16 is so lethal is because of its tumbling bullet...


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IAMLEGEND  [Team Member]
1/9/2007 11:51:22 PM
Part of it might be the old grain of truth and the keyholing of improperly stabilized 5.56X45mm projectiles of the wrong weight for the twist rate.




The result of unstabilized bullets:
A 1 in 12" FN-FNC firing M855 at 100 yards.
(Note the profiles cut out of the target).
DukeSnookems  [Team Member]
1/9/2007 11:52:32 PM
did they say in the air or in the body?
BlackDog714  [Team Member]
1/9/2007 11:53:17 PM

Originally Posted By DukeSnookems:
did they say in the air or in the body?


Both
crashburnrepeat  [Member]
1/9/2007 11:54:11 PM
in the body. I saw it too. They had this guy saying he didn't know anyone that had ever been hit by one cause it caused such massive damage.
Boomholzer  [Team Member]
1/9/2007 11:54:37 PM
Holy crap! It's lethal now???
Greenhorn  [Team Member]
1/9/2007 11:59:36 PM

Originally Posted By BlackDog714:
Watching "Guns: Machines of War" on the National Geographic Channel and their telling me the reason the M-16 is so lethal is because of its tumbling bullet...




Psst . . . "their" is posessive. "They're" is a contraction.
Kylaer_  [Member]
1/10/2007 12:11:43 AM

Originally Posted By crashburnrepeat:
in the body. I saw it too. They had this guy saying he didn't know anyone that had ever been hit by one cause it caused such massive damage.


Err...it does tumble in the body. So do all other spitzer-type bullets. Their centers of gravity are closer to the base than the tip, making them more stable when moving "backwards," and in a medium denser than air they will try to achieve this optimal configuration.

7.62x39 tumbles, .308 Winchester tumbles, .30-06 tumbles...the difference is in how much distance the bullet must travel through a solid medium before it tumbles, and in their behavior during tumbling. 7.62x39 will probably pass right through the body before it even gets to its tumbling point. 5.45 will tumble early but won't fragment. 5.56 will tumble and will fragment if the velocity is high enough, which is quite an effective wounding mechanism.
tyman  [Team Member]
1/10/2007 12:55:22 AM
Our CO said that the 5.56mm rounds is spinning so fast that it is just barely under the threshold of spinning itself completely apart and that if it went any faster, it would be out of control and unstable.

Silesius  [Member]
1/10/2007 12:57:46 AM
So, what is the correct answer?
Kylaer_  [Member]
1/10/2007 1:01:47 AM

Originally Posted By tyman:
Our CO said that the 5.56mm rounds is spinning so fast that it is just barely under the threshold of spinning itself completely apart and that if it went any faster, it would be out of control and unstable.



He's wrong, but his statement is based on a grain of truth. There have been situations where bullets came apart on leaving the muzzle; these were thin-jacketed, lightweight varmint ammo being fired out of a tight-twist barrel (1:7 I think is the only one that'll do it, 1:9 is safe). They do indeed come apart. But this does not happen with mil-spec 55-grain FMJ.
tyman  [Team Member]
1/10/2007 1:57:04 AM

Originally Posted By Kylaer_:

Originally Posted By tyman:
Our CO said that the 5.56mm rounds is spinning so fast that it is just barely under the threshold of spinning itself completely apart and that if it went any faster, it would be out of control and unstable.



He's wrong, but his statement is based on a grain of truth. There have been situations where bullets came apart on leaving the muzzle; these were thin-jacketed, lightweight varmint ammo being fired out of a tight-twist barrel (1:7 I think is the only one that'll do it, 1:9 is safe). They do indeed come apart. But this does not happen with mil-spec 55-grain FMJ.


I can assure you he has no idea about the twist rate and using lighter bullets in faster twists.

It was just drivel he's heard before and was trying to sound smart. Me and another guy who is really into guns just looked at each other and shook our heads.
thedoctors308  [Team Member]
1/10/2007 2:05:33 AM
It will exist as long as dumbasses shoot heavy ammo through slow twist bbls.
pcsutton  [Team Member]
1/10/2007 2:06:03 AM

Originally Posted By tyman:

Originally Posted By Kylaer_:

Originally Posted By tyman:
Our CO said that the 5.56mm rounds is spinning so fast that it is just barely under the threshold of spinning itself completely apart and that if it went any faster, it would be out of control and unstable.



He's wrong, but his statement is based on a grain of truth. There have been situations where bullets came apart on leaving the muzzle; these were thin-jacketed, lightweight varmint ammo being fired out of a tight-twist barrel (1:7 I think is the only one that'll do it, 1:9 is safe). They do indeed come apart. But this does not happen with mil-spec 55-grain FMJ.


I can assure you he has no idea about the twist rate and using lighter bullets in faster twists.

It was just drivel he's heard before and was trying to sound smart. Me and another guy who is really into guns just looked at each other and shook our heads.


If I remember correctly M188 62 gr leaves a 1:9 at something like 35,000 rpm. That's a lot of gyroscopic effect.
brouhaha  [Team Member]
1/10/2007 2:12:11 AM

Originally Posted By pcsutton:

Originally Posted By tyman:

Originally Posted By Kylaer_:

Originally Posted By tyman:
Our CO said that the 5.56mm rounds is spinning so fast that it is just barely under the threshold of spinning itself completely apart and that if it went any faster, it would be out of control and unstable.



He's wrong, but his statement is based on a grain of truth. There have been situations where bullets came apart on leaving the muzzle; these were thin-jacketed, lightweight varmint ammo being fired out of a tight-twist barrel (1:7 I think is the only one that'll do it, 1:9 is safe). They do indeed come apart. But this does not happen with mil-spec 55-grain FMJ.


I can assure you he has no idea about the twist rate and using lighter bullets in faster twists.

It was just drivel he's heard before and was trying to sound smart. Me and another guy who is really into guns just looked at each other and shook our heads.


If I remember correctly M188 62 gr leaves a 1:9 at something like 35,000 rpm. That's a lot of gyroscopic effect.


More like 350k.

edit- A bullet fired at 3000fps from a 1/7 rotates at 308,571 rpm
PsyWarrior  [Team Member]
1/10/2007 2:14:09 AM

Originally Posted By Kylaer_:

Originally Posted By crashburnrepeat:
in the body. I saw it too. They had this guy saying he didn't know anyone that had ever been hit by one cause it caused such massive damage.


Err...it does tumble in the body. So do all other spitzer-type bullets. Their centers of gravity are closer to the base than the tip, making them more stable when moving "backwards," and in a medium denser than air they will try to achieve this optimal configuration.

7.62x39 tumbles, .308 Winchester tumbles, .30-06 tumbles...the difference is in how much distance the bullet must travel through a solid medium before it tumbles, and in their behavior during tumbling. 7.62x39 will probably pass right through the body before it even gets to its tumbling point. 5.45 will tumble early but won't fragment. 5.56 will tumble and will fragment if the velocity is high enough, which is quite an effective wounding mechanism.


You may want to study terminal ballistics a little more. The spin on the bullet (gyroscopic force) over rides the tail heavy aspect of the bullet. This si the reason a rocket (with a gyroscope mounted inside) can maintain flight when all the force of thrust is applied directly to the tail. The rocket itself does not spin, but the gyroscope inside provides the stability provided the bullet by a properly rifled barrel. Fire a round into ballistic gelatin and tell me how much tumble your mil-spec bullet has when fired from a 1 in 9 twist barrel. Poor ballistic design (matching twist rates to ammo weights) causes tumbling and along with that tumbling, serious accuracy problems.
heathen  [Team Member]
1/10/2007 3:45:39 AM
I just had a guy look at a picture of an AK and tell me that it could be made full-auto if I filed down the firing pin. Yes, I set him straight and informed him that it was the disconnect that needed filed instead. Just kidding. I set him straight and told him the truth.
vito113  [Team Member]
1/10/2007 4:05:52 AM
9 out of 10 skinnies who were still able to express a preference said they did not like being shot by an M16…


ANdy
injun-ear  [Team Member]
1/10/2007 6:57:37 AM

Originally Posted By brouhaha:

Originally Posted By pcsutton:

Originally Posted By tyman:

Originally Posted By Kylaer_:

Originally Posted By tyman:
Our CO said that the 5.56mm rounds is spinning so fast that it is just barely under the threshold of spinning itself completely apart and that if it went any faster, it would be out of control and unstable.



He's wrong, but his statement is based on a grain of truth. There have been situations where bullets came apart on leaving the muzzle; these were thin-jacketed, lightweight varmint ammo being fired out of a tight-twist barrel (1:7 I think is the only one that'll do it, 1:9 is safe). They do indeed come apart. But this does not happen with mil-spec 55-grain FMJ.


I can assure you he has no idea about the twist rate and using lighter bullets in faster twists.

It was just drivel he's heard before and was trying to sound smart. Me and another guy who is really into guns just looked at each other and shook our heads.


If I remember correctly M188 62 gr leaves a 1:9 at something like 35,000 rpm. That's a lot of gyroscopic effect.


More like 350k.

edit- A bullet fired at 3000fps from a 1/7 rotates at 308,571 rpm


308571.428572 rpm.

Significant figgerz, dude.*

*I had a professor who'd completely freak over our answers.
Keith_J  [Team Member]
1/10/2007 7:11:00 AM

Originally Posted By PsyWarrior:

Originally Posted By Kylaer_:

Originally Posted By crashburnrepeat:
in the body. I saw it too. They had this guy saying he didn't know anyone that had ever been hit by one cause it caused such massive damage.


Err...it does tumble in the body. So do all other spitzer-type bullets. Their centers of gravity are closer to the base than the tip, making them more stable when moving "backwards," and in a medium denser than air they will try to achieve this optimal configuration.

7.62x39 tumbles, .308 Winchester tumbles, .30-06 tumbles...the difference is in how much distance the bullet must travel through a solid medium before it tumbles, and in their behavior during tumbling. 7.62x39 will probably pass right through the body before it even gets to its tumbling point. 5.45 will tumble early but won't fragment. 5.56 will tumble and will fragment if the velocity is high enough, which is quite an effective wounding mechanism.


You may want to study terminal ballistics a little more. The spin on the bullet (gyroscopic force) over rides the tail heavy aspect of the bullet. This si the reason a rocket (with a gyroscope mounted inside) can maintain flight when all the force of thrust is applied directly to the tail. The rocket itself does not spin, but the gyroscope inside provides the stability provided the bullet by a properly rifled barrel. Fire a round into ballistic gelatin and tell me how much tumble your mil-spec bullet has when fired from a 1 in 9 twist barrel. Poor ballistic design (matching twist rates to ammo weights) causes tumbling and along with that tumbling, serious accuracy problems.


Look at the highlighted sections above in Kylaer's posting. He gave the limitations and stated that tumbling happens when the bullet is traveling through a medium that is denser than air.
VTHOKIESHOOTER  [Team Member]
1/10/2007 7:17:26 AM
I watched the show as well. They did not say that it tumbled in the air, only that the mast moving projectile will yaw because of the weight in the rear (they used the titanic sinking as an example) and fragment once the bullet reached 90 degrees. I honestly didn't see anything wrong with what they said, although they should have pointed out that fragmentation ranges will vary with ammo type and length of barrel.
Ragnaroc  [Member]
1/10/2007 7:33:30 AM
I once shot a black bear in the tail that was angling away from me at about 15 degrees with a 55gr solid.
The bullet traveled 3/4 of the way up the spine, turning it to mush. I always assumed that tumbling is what helped the bullet take a right turn.
Most 55's recovered from animals, in my experience, have the front half bent at a good angle with lead mashed out and the back half disintigrated.
And, to anyone who takes exception to me shooting a black bear with .233, you don't know the circumstances, so just kyms.
Magurgle  [Team Member]
1/10/2007 7:36:32 AM

Originally Posted By injun-ear:

Originally Posted By brouhaha:

More like 350k.

edit- A bullet fired at 3000fps from a 1/7 rotates at 308,571 rpm


308571.428572 rpm.

Significant figgerz, dude.*

*I had a professor who'd completely freak over our answers.



Wouldn't that be 3x10^5 rpm then
LWilde  [Team Member]
1/10/2007 8:58:01 AM

Originally Posted By vito113:
9 out of 10 skinnies who were still able to express a preference said they did not like being shot by an M16…


ANdy




bcw107  [Member]
1/10/2007 9:04:36 AM

Originally Posted By VTHOKIESHOOTER:
I watched the show as well. They did not say that it tumbled in the air, only that the mast moving projectile will yaw because of the weight in the rear (they used the titanic sinking as an example) and fragment once the bullet reached 90 degrees. I honestly didn't see anything wrong with what they said, although they should have pointed out that fragmentation ranges will vary with ammo type and length of barrel.


That's exactly what he said. By the way "he" is Ken Elmore of Specialized Armament. If you have the opportunity to take a class of his, do it. He is knowledgeable and a character, funny as hell and can use the "f" word as every part of speech.
hughjafj  [Team Member]
1/10/2007 9:05:09 AM
My Brother-in-law is a former Marine and everytime this comes up tells me he saw the keyholed targets while working the pits with his own eyes. This could happen because of worn muzzles right?
UH_SALT_RIFLE  [Team Member]
1/10/2007 9:06:19 AM
As I wathced the show all I could think was "I wonder how many people from ARFCOM are watching this?"
Hellhound  [Team Member]
1/10/2007 9:10:48 AM

Originally Posted By UH_SALT_RIFLE:
As I wathced the show all I could think was "I wonder how many people from ARFCOM are watching this?"










That was on National Geographic. On Sunday at 9 I think they are having a program about security contractors in Iraq. I set a reminder for myself to check it out.
markm  [Team Member]
1/10/2007 9:14:14 AM
Oh it tumbles, BABY!

Get over it!
colesteele  [Member]
1/10/2007 9:15:28 AM

Originally Posted By hughjafj:
My Brother-in-law is a former Marine and everytime this comes up tells me he saw the keyholed targets while working the pits with his own eyes. This could happen because of worn muzzles right?


Possibly, but more likley that happens when the wrong ammo is used with the wrong barrell twist, ie. green tip, 62 gr A2 ammo or better in a 1:12 twist A1. I've seen it too, but only on a 25m target. What is amazing is that the bullet actually hit the target at that range. How long ago was your BIL in the Marines.
Ghetto  [Team Member]
1/10/2007 9:17:12 AM

Originally Posted By UH_SALT_RIFLE:
As I wathced the show all I could think was "I wonder how many people from ARFCOM are watching this?"


+1

..and as soon as the M16 part came on my phone started ringing
eswanson  [Member]
1/10/2007 9:21:08 AM

Originally Posted By UH_SALT_RIFLE:
As I wathced the show all I could think was "I wonder how many people from ARFCOM are watching this?"


I caught the part about the M16. I didn't think it was that bad, from my recollection they stated pretty clearly that the tumbling was inside the body, not as the round flew through the air. And they didn't even really show it as "tumbling"; the graphic they used showed the bullet turning sideways and coming apart.
AFARR  [Team Member]
1/10/2007 9:21:12 AM
Let's say that target looks AWFUL familiar......

FNC has a fairly slow twist rate (1 in 14"?), and the target was from a full auto FNC...if it is really my target (I thought I have it stored somewhere), it was probably at 25 yards, not 100 yards as listed, and it was a magazine of M855 (green tip) ammo fired through the rifle. The twist was too slow to stabilize the heavier rounds. I did have some Black Hills target stuff with me that day, and some rounds might have been their heavier rounds.

AFARR

(Sadly, the rifle was sold long ago to pay tuition expenses....)

Better Picture:
Old_Painless  [Team Member]
1/10/2007 9:23:34 AM
I watched it. There were a few errors, but the statements about tumbling were correct.

He did not say it tumbled in flight. He (correctly) stated that when it hit flesh, it yawed and broke at the cannalure, and then fragmented.

That's exactly what it does. They even had a cartoon video that demonstrated how it occurs.

The 5.56 does not tumble in flight unless there is something really wrong with the gun or the ammo. But it does indeed tumble (yaw is a better term) when it hits the target.

Read about the details in the: Ammo Oracle
Shootingcpl  [Member]
1/10/2007 9:42:07 AM

Originally Posted By UH_SALT_RIFLE:
As I wathced the show all I could think was "I wonder how many people from ARFCOM are watching this?"


I saw it also the history of the machine gun and battle tactics was pretty good

And he did not say the bullet tumbled in flight but after it hit flesh!
graywolf  [Team Member]
1/10/2007 9:48:30 AM
back in the 60s they use to say, when it hits bone it will follow the bone by tumbling
alexfiggy  [Member]
1/10/2007 9:48:39 AM
this topic is funny and i love it when it comes up.im a former active duty marine and a operation restore hope and distant runner (thats when we went to rawanda and burundi)11 meu west pac 93-94 vet. i havent seen any wounded skinnys talking about being hit by 556 but seen plenty of our gi surviving 762 hits.i wonder why?i have shot everything with 556 from coons to hogs and deer it works . its not a ray gun.but it will kill.im a firefighter/paramedic for the 6 largest fire/rescue dp in the country and you would be suprised how much pain and damage a body can take before it gives out.i wish people would jusst stop talking crap about this subject 556 will do a number on you and if you dont belive then have the balls to stand infront of a 556 round. i cant wait until we kick out some 10mm caseless api full auto pulse rifles to handle the next set of bad guys or alians.
Coolio  [Member]
1/10/2007 10:27:06 AM

Originally Posted By Kylaer_:

Originally Posted By crashburnrepeat:
in the body. I saw it too. They had this guy saying he didn't know anyone that had ever been hit by one cause it caused such massive damage.


Err...it does tumble in the body. So do all other spitzer-type bullets. Their centers of gravity are closer to the base than the tip, making them more stable when moving "backwards," and in a medium denser than air they will try to achieve this optimal configuration.

7.62x39 tumbles, .308 Winchester tumbles, .30-06 tumbles...the difference is in how much distance the bullet must travel through a solid medium before it tumbles, and in their behavior during tumbling. 7.62x39 will probably pass right through the body before it even gets to its tumbling point. 5.45 will tumble early but won't fragment. 5.56 will tumble and will fragment if the velocity is high enough, which is quite an effective wounding mechanism.


It doesn't really tumble. Not if what you mean is a continuous summersaulting type motion.
What spitzer type bullets do is TURN 180 degrees and travel base first at some point after entering a target medium. In the case of cannelured .224" diameter bullets, this turning causes the bullet to break up (provided it is still traveling fast enough). Otherwise, it just turns around base first.
IAMLEGEND  [Team Member]
1/10/2007 10:13:27 PM

Originally Posted By AFARR:
Let's say that target looks AWFUL familiar......

FNC has a fairly slow twist rate (1 in 14"?), and the target was from a full auto FNC...if it is really my target (I thought I have it stored somewhere), it was probably at 25 yards, not 100 yards as listed, and it was a magazine of M855 (green tip) ammo fired through the rifle. The twist was too slow to stabilize the heavier rounds. I did have some Black Hills target stuff with me that day, and some rounds might have been their heavier rounds.

AFARR

(Sadly, the rifle was sold long ago to pay tuition expenses....)

Better Picture:
i22.photobucket.com/albums/b344/JohnFootDr/IMG_1433.jpg


NO WAY!!!!!!!

That picture I posted is actually of YOUR target?!

Cool!
pogue  [Member]
1/10/2007 10:26:02 PM

Originally Posted By tyman:
Our CO said that the 5.56mm rounds is spinning so fast that it is just barely under the threshold of spinning itself completely apart and that if it went any faster, it would be out of control and unstable.




Ask your CO how a 22-250 manages to get a bullet down range.
Izzman  [Team Member]
1/10/2007 10:34:30 PM
I believe I watched this last night, was it the same one with the Brit firing the Maxim MG at the pink balloons?

If so, did you notice his fingers over the triggers as the guys were still setting balloons?, and then him yelling at the guys to get out of the way, and then firing very shortly after they moved from the area?

I am sure this was all in the editing, but it looked like he was laying down fire just seconds after they got out of the immediate way, and were still in his general direction of fire when he commenced firing!

I was like wtf?, Did he just do that.....
USGI_45  [Member]
1/10/2007 10:41:33 PM

Originally Posted By alexfiggy:
this topic is funny and i love it when it comes up.im a former active duty marine and a operation restore hope and distant runner (thats when we went to rawanda and burundi)11 meu west pac 93-94 vet. i havent seen any wounded skinnys talking about being hit by 556 but seen plenty of our gi surviving 762 hits.i wonder why?i have shot everything with 556 from coons to hogs and deer it works . its not a ray gun.but it will kill.im a firefighter/paramedic for the 6 largest fire/rescue dp in the country and you would be suprised how much pain and damage a body can take before it gives out.i wish people would jusst stop talking crap about this subject 556 will do a number on you and if you dont belive then have the balls to stand infront of a 556 round. i cant wait until we kick out some 10mm caseless api full auto pulse rifles to handle the next set of bad guys or alians.




Medical care
VTHOKIESHOOTER  [Team Member]
1/11/2007 7:45:54 AM

Originally Posted By Izzman:
I believe I watched this last night, was it the same one with the Brit firing the Maxim MG at the pink balloons?

If so, did you notice his fingers over the triggers as the guys were still setting balloons?, and then him yelling at the guys to get out of the way, and then firing very shortly after they moved from the area?

I am sure this was all in the editing, but it looked like he was laying down fire just seconds after they got out of the immediate way, and were still in his general direction of fire when he commenced firing!

I was like wtf?, Did he just do that.....
Now THAT was one of the parts of the show that was stupid, stupid, stupid.

Also, did anyone doubt that the Maxim coudln't cut down the tree? Talking about a no brainer.
tyman  [Team Member]
1/11/2007 7:54:13 AM

Originally Posted By pogue:

Originally Posted By tyman:
Our CO said that the 5.56mm rounds is spinning so fast that it is just barely under the threshold of spinning itself completely apart and that if it went any faster, it would be out of control and unstable.




Ask your CO how a 22-250 manages to get a bullet down range.


I try my best to NOT talk to him at all. Lets say that I dont really know of anyone besides his drinking buddy (My Plt. Sgt) that likes him in our Co.
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