Do 5.56 fmj often break up when they hit flesh or water?

[2damnold4this]

M855 certainly depends on yaw for wounding as do many other FMJ military bullets. Hunting bullets do not depend on yaw for wounding.

The US Army claims the new M855a1 bullet is not dependent on yaw:

The Army tackled the consistency issue by focusing on the yaw of a projectile and how differences in yaw can influence results when striking soft targets. The M855 round, similar to the Army's M80 (7.62mm ball round), is a "yaw-dependent" bullet. As any bullet travels along its trajectory, it "wobbles" in both pitch and yaw, causing the projectile to strike its target at different attitudes with virtually every shot.

For a yaw-dependent bullet such as the M855 or M80, this results in varying performance, depending upon where in the yaw/pitch cycle the bullet strikes its target. For example, at a high angle of yaw, the M855 performs very well, transferring its energy to the target in short order. At a low angle of yaw, however, the bullet reacts more slowly, causing the inconsistent effects observed in the field.

The M855A1 is not yaw-dependent. Like any other bullet, it "wobbles" along its trajectory. However, the EPR provides the same effects when striking its target, regardless of the angle of yaw. This means the EPR provides the same desired effects every time, whether in close combat situations or longer engagements. In fact, the U.S. Army Research Laboratory (ARL) verified through live-fire tests against soft targets that, on average, the M855A1 surpassed the M80 7.62mm round. The 7.62mm, although a larger caliber, suffers from the same consistency issue as the M855, but to a higher degree.
https://www.army.mil/article/48657/evolution_of_the_m855a1_enhanced_performance_round

 

[tangolima]

M855 certainly depends on yaw for wounding as do many other FMJ military bullets. Hunting bullets do not depend on yaw for wounding.



The US Army claims the new M855a1 bullet is not dependent on yaw:



The Army tackled the consistency issue by focusing on the yaw of a projectile and how differences in yaw can influence results when striking soft targets. The M855 round, similar to the Army's M80 (7.62mm ball round), is a "yaw-dependent" bullet. As any bullet travels along its trajectory, it "wobbles" in both pitch and yaw, causing the projectile to strike its target at different attitudes with virtually every shot.



For a yaw-dependent bullet such as the M855 or M80, this results in varying performance, depending upon where in the yaw/pitch cycle the bullet strikes its target. For example, at a high angle of yaw, the M855 performs very well, transferring its energy to the target in short order. At a low angle of yaw, however, the bullet reacts more slowly, causing the inconsistent effects observed in the field.



The M855A1 is not yaw-dependent. Like any other bullet, it "wobbles" along its trajectory. However, the EPR provides the same effects when striking its target, regardless of the angle of yaw. This means the EPR provides the same desired effects every time, whether in close combat situations or longer engagements. In fact, the U.S. Army Research Laboratory (ARL) verified through live-fire tests against soft targets that, on average, the M855A1 surpassed the M80 7.62mm round. The 7.62mm, although a larger caliber, suffers from the same consistency issue as the M855, but to a higher degree.

https://www.army.mil/article/48657/evolution_of_the_m855a1_enhanced_performance_round

Interesting. Sounds like they purposely "lousied up" the bullet to make it wobble all the way in flight. I heard that M855 bullet's accuracy is not pristine, and my own limited experience loading it confirms that. The new M855A1 is a non-lead version of the bullet, and its length has increased from 0.9" to 0.98". It is still stable with 1:7 twist, but just a bit less.

Hunting bullets expand upon impact. Yawing is not needed for their terminal ballistic effects. But is yawing + expansion different from expansion alone?

-TL

Sent from my SM-N960U using Tapatalk

 

[Skans]

Jacketed bullets, even hollow-points do not break up unless they were designed to break up. I'm not even sure if there were ever any 5.56 frangible rounds. Here is a picture a frangible round that is designed to break up in impact. They were designed for shooting at steel targets so that the targets would not be damaged.

 

[davidsog]

Yawing is indeed the most important mechanism transfers energy to the target.

Wound ballistics are complicated affairs. The Army draws their conclusion about yaw as yaw is the primary method the bullet imparts Kinetic Energy to the target in the portions of flight the bullet is yawing. Statistically the design of the bullet was insignificant to the lethality. Bullet design is mostly a marketing gimmick with some exception.

That would be in the beginning of the flight in the first 100 meters or so and towards the end of the flight.

In that portion yaw effects impart the lion's share of KE.

In the portion of flight that bullet is stable, then ability to expand can be a factor. However, bullets tend to yaw upon impact with flesh and if that occurs it will still be the mechanism to impart the lions share of KE to the target.

Yaw is the principle means of delivering KE to the target for most bullets. Notice the number one reason for KE transfer is yaw.

The loss of kinetic energy by the projectile is influenced by a variety of factors: • The more unstable the flight of the projectile (the greater the angle of yaw) at the moment of impact with the body, then the greater the loss of KE. • Wobble and tumbling of the bullet in the body increases KE loss.

Bullet expansion does impart KE on the target. The differences are present and measurable. The differences in wound mechanics are statistically insignificant.

The caliber and shape of the projectile influence the "drag effect" in tissues and thus the loss of KE. • The structure of the bullet influences bullet deformation and break-up both of which result in greater loss of KE. • High velocity projectiles are more likely to break up than low velocity projectiles.

Bullet shape matters especially in the portion of flight the bullet has achieved stability and if the bullet does not yaw upon impact. In many cases expansion based bullets transfers more energy at the expense of penetration.

The longer the wound track through the body, the greater the loss of stability and the greater the deformation of the projectile with resultant increased loss of KE. • The denser the tissue through which the projectile passes, the greater the retardation of the projectile and thus the greater the loss of KE.

https://www.slideserve.com/wylie-rice/gunshot-wounds

The Army Engineers say there is no statistically significant difference due to bullet design.

They did not say they are the same, they say the differences do not matter and do not affect the overall outcome.

First of all, this argument becomes stupid at some point because you cannot make something more dead once it has sustained a fatal wound. Dead is dead. Incapacitation is another story but in terms of lethality, you can only achieve death.

Penetration is what wins gunfights. Nobody has ever lost a gunfight due to over penetration while you will definitely lose the fight for a lack of penetration. In terms of KE transfer, if you penetrate the target all the way thru, you have LOST the KE transfer fight. Your bullet definitely did not transfer the maximum amount of KE that was possible. That is on paper and has nothing to do with a losing a gunfight.

Even with all the penciling issue on that first tour, we never had a single bad guy be able to fight back or win the fight once hit. Don't get me wrong, it was not ideal nor fun as they certainly tried to fight back but it wasn't a unmitigated disaster that lost us the fight. It was just far from ideal and really unacceptable for certain scenarios.

In the portions of bullet flight that are stabilized and shooting at unarmored targets that do not shoot back or take cover then an expanding bullet would be better I can imagine. Can't prove it but it seems logical.

However, the Army did not study that. They studied the whole flight of the bullet including the portions of flight that are unstable. Under those circumstances, they found no significant differences in lethality based upon bullet design.

 

[2damnold4this]

Yawing is indeed the most important mechanism transfers energy to the target.

Not in bullets that aren't dependent on yaw like soft tipped hunting rifle rounds, hollow point pistol rounds, soft lead musket balls, other bullets designed to expand.

The Army draws their conclusion about yaw as yaw is the primary method the bullet imparts Kinetic Energy to the target in the portions of flight the bullet is yawing. Statistically the design of the bullet was insignificant to the lethality. Bullet design is mostly a marketing gimmick with some exception.

Is the Army peddling a gimmick when they say M855a1 wounds better than M855 ball in CQB because it's not dependent on yaw?

Yaw is the principle means of delivering KE to the target for most bullets. Notice the number one reason for KE transfer is yaw.

Only for yaw dependent bullets like M855, M193, and M80 ball.

Bullet expansion does impart KE on the target. The differences are present and measurable.

It sure does. That's why bullets that are designed to expand perform so much more reliably than yaw dependent bullets when it comes to wounding. We don't shoot deer with M80 ball because it's unreliable when it comes to wounding because it's yaw dependent. We use bullets that are designed to expand. There are plenty of those bullets available for 5.56/.223 and they have been for years.

Clearly a bullet that doesn't depend on the randomness of yaw to wound effectively is better than one that must depend on yaw and that's why hunters, law enforcement, and people concerned with self defense generally use bullets that are designed to expand.


All of these tests are due to complaints about M855 that penciled and the search for solutions. The Army says it has the solution with M855a1 and claims that it's not dependent on the whims of yaw for wounding.

There were plenty of commercial off the shelf bullets that weren't dependent on yaw for wounding available in 2008 when your paper couldn't find any significant difference in CQB wounding in them. One of them would become the M855a1 and was submitted in 2004 by Liberty Ammunition. That's the same M855a1 ball that the Army says fixes the problems with M855 because it's not yaw dependent while M855 is.


Edit to add: Liberty initially won a patent infringement lawsuit against the Army but lost on appeal. It's not the exact same bullet as the M855a1 as I wrote earlier. It is very similar.

 

[2damnold4this]

Hunting bullets expand upon impact. Yawing is not needed for their terminal ballistic effects. But is yawing + expansion different from expansion alone?

That is an interesting question.

 

[davidsog]

Not in bullets that aren't dependent on yaw like soft tipped hunting rifle rounds, hollow point pistol rounds, soft lead musket balls, other bullets designed to expand.

Sphere's yaw all the time.

In fact, in one of the few studies on Musket Ball wound Morphology and Treatment of Musket Ball Wounds says:

The ball would penetrate the body causing internal damage via ‘permanent’ and ‘temporary’ cavities. However, unlike modern bullets, often there was no ‘exit wound’ from a musket shot, as the soft lead musket ball would potentially flatten or be diverted from its trajectory within the body.

That diversion is Yaw....

You can see the nice curved path of the ball when this guy shoots a gel block.

https://youtu.be/pETiI1NKyeo?si=Pwrt8S1eSvfX49tr&t=264

It sure does. That's why bullets that are designed to expand perform so much more reliably than yaw dependent bullets when it comes to wounding. We don't shoot deer with M80 ball because it's unreliable when it comes to wounding because it's yaw dependent. We use bullets that are designed to expand. There are plenty of those bullets available for 5.56/.223 and they have been for years.

https://www.civilwarpetitions.ac.uk...ms-and-their-treatment-during-the-civil-wars/

And you have taken my comment completely out of context and without regard to the behavior of a bullet over its entire flight. Your view that bullets are stable over their entire path is not how it works.

That is why Weapon Engineers made the conclusion they did that bullet lethality has no statistically significant difference due to bullet design.

Again, nobody ever lost a firefight because of over-penetration but you will definitely lose the fight with a lack of penetration.

 

[davidsog]

But is yawing + expansion different from expansion alone?

Energy is finite and the bullet expends energy as it creates the wound cavity.

A bullet that expands creates a longer wound cavity and a little wider than a bullet that does not expand by a factor of the larger diameter from the expansion. The cavity will basically follow the normal shock boundaries and much of the tissue damage is caused by the energy transfer of that normal shock. That is why solid flat nosed bullets which exhibit very little bullet deformation cause such devastating wounds and are used for dangerous game. That flat nose creates what is termed a detached Bow Wave and creates a huge energy transfer to cross it. It is why Astronauts could survive a reentry in a space capsule.

A bullet that yaws creates a much larger wound cavity that the bullet. It trades energy to move forward to the side it is yawing away from creating a much larger diameter wound cavity than bullet expansion alone could ever produce.

 

[2damnold4this]

I think it's pretty clear that you don't know what you are posting about.


The wounding performance of a soft lead musket ball doesn't depend on the yaw angle it strikes the target like M193, M855, or M80 ball. A soft lead musket ball will flatten and may then yaw in tissue but it isn't dependent on a random yaw angle as it flies through the air and hits tissue.

 

[2damnold4this]

A bullet that expands creates a longer wound cavity and a little wider than a bullet that does not expand by a factor of the larger diameter from the expansion. The cavity will basically follow the normal shock boundaries and much of the tissue damage is caused by the energy transfer of that normal shock. That is why solid flat nosed bullets which exhibit very little bullet deformation cause such devastating wounds and are used for dangerous game. That flat nose creates what is termed a detached Bow Wave and creates a huge energy transfer to cross it.

A bullet that expands and a flat point solid bullet are both examples of bullets that are not dependent on yaw for wounding.

 

[44 AMP]

Every bullet that is longer than it is wide (in other words, every bullet, not round ball) is going to yaw. Pitch up or down, and yaw side to side, at some point. They "wobble" in flight, and tip when they hit something.

This is the nature of things. How much they tip and what the results of that are , depend on a host of other factors.

TO say a bullet "depends on yaw" is disingenuous, and only part of the story.

There is no question that a bullet that turns sideways increases its wound channel, because you have exchanged the small narrow (and often pointed) nose of the bullet for the entire side of the bullet, a significant increase in "frontal area".

This is also what an expanding bullet does, and what a large bore bullet starts out with, compared to a small bore one. As an extreme example, a .22 cal rifle bullet turned sideways still doesn't have the surface area of a 12ga slug pointed straight on.

Turn the bullet sideways, have it tumble in flesh, yes it increases the effect of the wound channel by making it larger than when the bullet goes through point first. But the bullet doesn't depend on that.

The SHOT depends on you, the shooter, putting the bullet in the right place. Do that and it works. Don't, and it often doesn't work as well as hoped.

 

[2damnold4this]

I think the point about yaw is that some US military ammunition performs inconsistently in tissue based on a random yaw angle it strikes tissue during flight. Shot placement is always important but hunting ammunition, soft lead round balls, hollow point defensive handgun rounds, hard cast lead, and other bullets aren't dependent on a random yaw variable for wounding in soft tissue like many US service rounds.



See this link:

link


The Army tackled the consistency issue by focusing on the yaw of a projectile and how differences in yaw can influence results when striking soft targets. The M855 round, similar to the Army's M80 (7.62mm ball round), is a "yaw-dependent" bullet. As any bullet travels along its trajectory, it "wobbles" in both pitch and yaw, causing the projectile to strike its target at different attitudes with virtually every shot.

For a yaw-dependent bullet such as the M855 or M80, this results in varying performance, depending upon where in the yaw/pitch cycle the bullet strikes its target. For example, at a high angle of yaw, the M855 performs very well, transferring its energy to the target in short order. At a low angle of yaw, however, the bullet reacts more slowly, causing the inconsistent effects observed in the field.

The M855A1 is not yaw-dependent. Like any other bullet, it "wobbles" along its trajectory. However, the EPR provides the same effects when striking its target, regardless of the angle of yaw. This means the EPR provides the same desired effects every time, whether in close combat situations or longer engagements. In fact, the U.S. Army Research Laboratory (ARL) verified through live-fire tests against soft targets that, on average, the M855A1 surpassed the M80 7.62mm round. The 7.62mm, although a larger caliber, suffers from the same consistency issue as the M855, but to a higher degree.

 

[davidsog]

TO say a bullet "depends on yaw" is disingenuous, and only part of the story.

So, Aberdeen Proving Ground Engineers are now disingenuous, LMAO.

Got it.

The M855A1 is not yaw-dependent.

Interesting. Sounds like they purposely "lousied up" the bullet to make it wobble all the way in flight.

It absolutely does not depend on whether the bullet has arbitrarily yawed in a good position to cause greater damage.

Yep, it consistently yaws to consistently to deliver consistent damage to the target. The penetrator is loose inside the copper bullet which causes asymmetrical force application and yaw. It is also designed to separate inside the target, leaving a portion of the bullet to cause a large wound cavity with a penetrator that continues to drive.

It does not depend on yaw because it is designed to yaw instead of just doing it as a byproduct of being shot out of a gun.

M855A1 came out of the research into improving 5.56mm lethality and is a result of this report:

https://apps.dtic.mil/sti/tr/pdf/ADA519801.pdf

And this one:

https://apps.dtic.mil/sti/pdfs/ADA530895.pdf

The reports where the Army concluded that bullet lethality is due to yaw.

 

[44 AMP]

The reports where the Army concluded that bullet lethality is due to yaw.

This must be true, the Army doesn't make mistakes!

That's what they told me, anyway (and repeatedly)

 

[davidsog]

This must be true, the Army doesn't make mistakes!

That's what they told me, anyway (and repeatedly)

Yep, feel free to go get you some equipment to measure in real time the flight positional information and path of bullets to dispute their findings.

 

[2damnold4this]

All bullets have some yaw in flight. Many bullets yaw in tissue.

Martin Fackler and others established that the wounding effect of M193, M855, M80 ball and some other bullets are dependent on what is a random yaw angle in flight that affects the wounding in tissue in CQB.

That is saying that sometimes these bullets would perform well in tissue and other times the bullets would just poke a hole without doing much damage. The bullets performance depended on the yaw angle in flight that it had when it struck tissue. Sometimes the bullets would work great and sometimes the bullets would pencil through soft tissue without causing much damage. When the term "yaw dependent" is used, it means bullets that rely on hitting the target while having the right yaw angle to do damage and not pencil through the target.

When the Army says the new M855a1 cartridge is not yaw depedent, it isn't saying that it doesn't yaw in flight or that it doesn't yaw in soft tissue. The Army is saying that the bullet doesn't depend on a particular yaw angle when it strikes the target to perform well in soft tissue.

It's a big benefit to have a bullet that doesn't depend on a random yaw angle to perform well in soft tissue but the civilian world has had bullets that are not dependent on yaw for many years.

 

[thallub]

Deleted. See my post dated 20 July, 2024.

 

[davidsog]

civilian world has had bullets that are not dependent on yaw for many years.

I believe that. Then again the Civilian Engineer designing a bullet has had absolutely no way to measure the actual flight path and flight attitude of a bullet in real time.

That lack of ability to accurately measure is why when an object is dropped, it does not accelerate towards the ground but rather the ground rises up to meet it.

People believe that too.

 

[2damnold4this]

https://youtu.be/h6MHG2cbZ7E?si=WVgyYAHmimnwEZgm

 

[davidsog]

He is literally talking about the data Aberdeen gathered in from the late 80's to mid 2000's.

And how agency's are ignoring it because some youtuber shot a pot roast in his backyard.