Does the 223 tumble?

[Shawn Thompson]

All spin-stabilized projectiles experience yaw, to some degree.

Imagine throwing a spinning wooden top down on a table; bullet yaw is very much the same. The first few meters out of the muzzle will show a rapid shift up to several degrees before settling down into "stabilized flight". As the projectile continually slows in velocity yaw will become proportionally greater, until it reaches a point of destabilization. Again this is a characteristic of all spin-stabilized projectiles and not just limited to the 5.56. Obviously, bullet weight, velocity and distance are all determining factors.

The question becomes, where along the bullets trajectory did it strike the intended target? Did it occur during stabilized flight? As the bullet slowed and experienced increasing yaw? Or out so far that the bullet had completely destabilized and was "tumbling"?

In addition, what is the projectile doing at short range? Remember there is rapid shifting the first few meters from the muzzle prior to stabilized flight? This is part of the reason why testing results varied so greatly from agency to agency when conflicts in urban environments became more prevalent, and concerns over the terminal ballistcs at the distances presented by those environments increased.

It is true, the effcts of a destabilizing bullet may work in our favor; however, it my also work against us. Understanding this concept, at least in part, has eventually prompted us to teach the concept of controlled pairs in our own carbine classes.

 

[GeauxTide]

Yep, two buddies came home from PI in 1967 telling me the tumble story. When I explained the truth of the matter, they were perplexed - " how could a Gunny be wrong"? Oh, boy..........

 

[ozarkrecluse]

Be very careful making statements like "we all know...." Particularly when you don't have an idea about what you're talking about.

 

[RT]

 

[603Country]

One thing mentioned above that didn't make sense to my engineering brain is the statement made more than once that attempts to explain why a bullet would tumble - specifically the part where it was stated that "the front of the bullet slows down more than the back of the bullet". Huh? Now maybe once the bullet goes off axis, the back of the bullet passes the front of the bullet, but that's after tumbling begins and not the cause of why tumbling began. So unless the FMJ bullet begins to compress linearly as it strikes the target, the front of the bullet and the back of the bullet will slow down at exactly the same rate as long as it stays on axis.

Anyway, I'm glad that this tumbling baloney is finally put to rest, or at least till the next guy brings it up in a month or two.

 

[Mike Irwin]

"specifically the part where it was stated that "the front of the bullet slows down more than the back of the bullet". Huh?"

I can understand the confusion. Hopefully I can explain it in a way that makes sense...

It's not that the front slows down faster that causes the bullet to tumble. As a solid object, we know that's simply not possible unless the bullet rivets or bends in the middle.

What happens is that the front of the bullet TRIES to slow down faster. It has less mass than the rear of the bullet, which naturally wants to keep moving.

Because the front of the bullet tries to slow down faster than the rear, it quickly becomes unstable, and that's when it starts to tumble.

A bullet in flight is actually something of an unnatural thing, made possible only by the stabilization imparted by the rifling.

If you take an object that is weighted at one end (say a pipe with a chunk of lead in one end) and throw it like a javelin with the heavy end to the rear, it's going to flip over in flight and will almost always hit the ground heavy end first. In essence, the pipe tumbled in midair.

That's what's happening with a bullet when it starts to tumble in flesh.

 

[Jeff56]

A wise man knows which half.

.

I would think in this case the informed man would know which half. Obviously I'm not one of them informed types on this question.

It would seem to me that the front half of a bullet would slow down quicker if it hit the target at anything less than a perfect spiral. And I've seen enough keyholes to know that isn't always the case. If the front half hits first and it's off axis even just a little it will naturally start to spin out of control faster. The back half would slow down quickly as it strikes the target but the front half is continuing to reduce speed from contact with the mass of the target. If it was much of a deflection off a perfect spin the bullet would probably tumble pretty quickly. If it's just a minor keyhole issue I would think it wouldn't make a whole lot of difference in how the bullet starts to tumble.

Just from throwing sticks as a kid I think I've seen this bit of physics. You throw a stick trying to make it fly like a spear and if it hits offline just a little the back end of the stick comes around and whacks what you hit with the front end of the stick - you have a tumbling situation. If you hit straight into the target with your stick it pretty much dead stops right at that point (unless it's your best friend's eyeball and you just put it out ).

 

[DPris]

Years ago I fired a standard 9mm 115 FMJ and a standard .223 55 FMJ, both from 16-inch ARs, into my penetration box which uses 8-inch squares of one-inch pine laid in a row about half an inch apart.

The 9 penetrated farther, the .223 came to rest with its nose pointing back toward me.

There was clear evidence of tumbling as the .223 ran through successive boards before it finally stopped.

The 9 traveled nose-first till it stopped.

I recall being told in AF basic training in '72 that the 5.56 FMJs tumbled.
In flight, obviously no. In some target materials, yes.
Denis

 

[bonessssssssssssssss]

AR15 Ammo

I read somewhere early M16 had a barrel twist of 1/20 which with a 55 grain would make the bullet tumble.

 

[LineStretcher]

I read somewhere early M16 had a barrel twist of 1/20 which with a 55 grain would make the bullet tumble.

Perhaps tumble isn't the correct term because what actually happened was that they didn't stabilize. A twig or a branch would send them askew but if they hit a human they tumbled and got the job done. Later, when twist rates became tighter, they often just created knitting needle sized holes unless they hit bone. I honestly believe that politicians and lobbyists money is the only reason it's still around in our military.

 

[RC20]

The 5.56 was never designed to tumble before reaching it's target. It didn't ever tumble before reaching the target. It can tumble after it hits the target but all bullets can. Some say the 5.56 was designed to tumble on impact but it's actually designed to fragment on impact if you're talking military bullets. That's the only thing I've ever heard that ammo was designed to do. It could be it wasn't really designed to do that either.

Ahh the Mythings continue.

Putting it in context, a USAF guy saw a water mellong blow up and being a Pilot decided he needed his troops to ahve something tghat whiz bang cool (saly like many pilot he thought his thoughts were important)

Next the guy in charge of making everyting comoln (McNamer) decided this was the wave of the fture and ordered a new relaively untested gun into producion and snet it to the Ungles of Vietnam as the whiz bang solution (another profesion who thinks thei rhought are imporant and better than all else)

Along tghe way the wonder gun rep grew, it does not need to be cleaned and we can submsitue chape powder.

From Nam the answer came back, you can call BS good fertilizer but that does not make it so.

So what part of this thought process train wreck would you think lent itself to any though about what did or did not work.

The cold hard reality was that the 20 inch M-16 has a projectile that was marginally stable at 100 yards due to its twist, velocity (and the 55 gr size)

This then indeed did upset when it hit someone. Oh that is so cool.

Oh, by the way this thing is supposed to penetrate a steel helmet at 400 yards. And it fragments of course just as it gets to the brain behind the helmet, man that is so cool.

The problem is that at 125 yards it just poked holes in smaller frame men (some, known as VC, NVR.

Any hunter will tell you a gibven bullet will do certain things with its velicy area, then it quits doing t hose things. Too close and it will go right through, small hole.

Too far and it does not expand.

And that does not mention the, oh, we need a carbine (20 inch is not a carbine?) so the velocity goes down, oh we need a heavier bullet (so the stability changes) and oh, the twist is wrong because it won't shoot tracers (we really need to shoot those?)

the only hard news is that reality is tough and Mythings continue.

 

[jmr40]

Pointed bullets are heavier in the rear than the front. RN projectiles have their weight more evenly distributed. When they hit anything pointed bullets become unstable easier than nose heavy RN bullets.

The light bullets, slow twist and high velocity of pointed FMJ bullets did create some tumbling after they entered flesh and bone during the early M-16 days. I doubt if it was be design, but it still happened, at least at close range.

Modern heavier bullets with faster twist rates are less likely to tumble. It is a trade off. The lighter bullets might have put down a threat faster, but the heavier bullets will penetrate better, especially at longer ranges.

 

[thallub]

i often hunt wild hogs using the M193 5.56mm ball round. Why? Because it kills hogs more consistently than any other 5.56mm/.223 round i've used. It's also cheap.

When fired from a 20 inch or longer barrel, at ranges to about 150 yards, the bullet penetrates 4-6 inches, tumbles and fragments; destroying the heart and lungs and sometimes lacerating the diaphragm and liver.

http://kjg-munition.de/Zielwirkung/military_bullet_wound_patterns.html

 

[Jim Watson]

I read somewhere early M16 had a barrel twist of 1/20 which with a 55 grain would make the bullet tumble.

No.

The first M16s had a 14 twist just like the .222, .222 Magnum and every other .22 centerfire later than the Hornet. That will stablilize a 55 gr flatbase spitzer or a 52 gr boattail spitzer with no trouble. Those varmint bullets are meant to expand if not fragment on impact, no "tumble" involved.
It will get by with the M193 boattail FMJ in temperate climates, but the military found out that stabilization was marginal and accuracy poor in cold dense air. Rumor has it that it gets cold in Northern Europe.
So they went to a 12 twist for that relatively long (and generally cheaply made) bullet.

"Tumbling" gives an impression of the bullet flipping end over end like a midget buzz saw. What really happens is that the bullet "yaws" and turns over on impact, penetrating a torso sideways or base first. Fracture at the cannelure at closer ranges is another source of nasty wounds, but is unlikely past about 150 yards. The German 7.62 bullet had a deep cannelure thought to intentionally enhance fragmentation. They said not, of course.

Lots of soldiers said the small change in twist rate caused a significant reduction in lethality. But then there was the Army surgeon who patched up a lot of people in Viet Nam and said that you could not tell a difference in bullet wounds by the caliber. Too much individual variation in other conditions. Well, that doesn't count the poor guy who was brought in with an unexploded 40mm grenade imbedded in his body. They got that out by reaching over sandbags stacked around the operating table.

 

[thallub]

What really happens is that the bullet "yaws" and turns over on impact, penetrating a torso sideways or base first

No.

The bullet yaws and breaks up after penetration. i've seen it too many times while field dressing hogs. Dr. Fackler says to too:

As shown on the wound profile, this full-metal-jacketed bullet travels point-forward in tissue for about 12cm after which it yaws to 90°, flattens, and breaks at the cannelure (groove around bullet midsection into which the cartridge neck is crimped).

 

[44 AMP]

Every bullet that is longer than it is wide may "tumble" after impact. This begins as a "yaw", and will turn into a full end for end "tumble" IF the bullet penetrates deeply enough in the target.

The .223/5.56 got the reputation for it, but all can do it, including the regular .30 cal bullets. What differs is the amount of distance through the target that is traveled before the bullet "tumbles".

.30s don't usually show tumbling until after they have passed through most people, so it is something seldom SEEN. .223s usually do within a person's body thickness, so docs and GIs often SEE the results of the tumble, and the legend is born.

The hype about tumbling was promoted during Viet Nam, to try and counter balance the (natural) lack of faith in the bean counter's ".22" which wasn't even legal for deer hunting in most states. Guys who had been using .30-06 and .308 were given .22s and told "they work just as well, because the bullet tumbles, they hold more ammo and kick less"

I suppose 2 out of three, ain't bad...

One thing mentioned above that didn't make sense to my engineering brain is the statement made more than once that attempts to explain why a bullet would tumble - specifically the part where it was stated that "the front of the bullet slows down more than the back of the bullet".

I think the part that is missed is that when a bullet hits something, there is resistance. And this does try to slow down the nose before the base, but that isn't what causes the yaw. The yaw comes from the fact that the force acting on the nose of the bullet isn't perfectly concentric. Even the bullet tip might not be perfectly concentric with the centerline. SO, the force of resistance is (at a minimum) SLIGHTLY off center, and this is what forces the nose of the bullet off center, and we call it "yaw". How much you get depends on a host of variables, but the principle holds. Once in a target medium (gel, flesh etc) the tiny bit of off center force is added to, by the movement of the bullet at speed, through the material, until it results in enough "yaw" to turn the bullet sideways, and then the more massive back end of the bullet takes over, and kind of "pulls" it along.

hope this helps...

 

[tmd47762]

Plus you add gyroscopic procession to instigate some yaw and balance yawing tendencies against the angular momentum determined by caliber (radius of bullet), density, and rotational speed.

 

[Paul B.]

Dunno how much help this will be but quite a few years ago My son in law and I took his Colt AR sporter out and ran shots into bundles of very well soaked newspaper. Then we looked for the bullets which were from military issue 5.56 with the 55 gr. FMJ bullet. IIRC we shot about ten rounds. A couple had broken in half and the rest were bent in a banana shape showing that they obviously tumbled. It didn't prove much of anything other than satisfy our curiosity of what had been said about that bullet. IIRC, the AR Sporter has a 20' 1 in 12" twist barrel. Penetration ran around 4 to 6" as I recall
Paul B.

 

[Bartholomew Roberts]

I can’t tell you how exciting it is to see an eight year old thread revived with an ignorant post that had already been adequately explained/debunked on the first page of a two page thread.

 

[ThomasT]

Bart I almost got sucked in to this thread myself till I saw how old it was. Then I saw as expected it was drug up by a new guy. It must be a rite of passage for a newby to start off their posting career by reviving a long dead thread.