Ah! rumors about the early M16's "unstable bullet"

[WhyteP38]

Interesting. Since the ammo was a caliber they couldn't use, did they dig up the ammo for the components? It's difficult to see how the ammo would help them, unless they used the components for some sort of anti-personnel IED.

[CrazyLarry]

most likely for rifles they had stolen through working on base maybe or picked up after a firefight. They had plenty of our rifles

[HorseSoldier]

My understanding is that the VC were pretty opprotunistic as far as weaponry goes, including stuff captured from US or ARVN units, so they probably could find some use for 5.56mm ammunition if it was remotely servicable.

Edit to add, "What CrazyLarry said."

[WhyteP38]

Interesting. I've read several accounts from 'Nam vets claiming the VC and NVA avoided picking up M-16s because of the supposed problems with the gun and the round at that time. However, those accounts were also written by vets who didn't like the gun and the round, so maybe their accounts were mostly BiaSed.

[JR47]

The NVA weren't as interested in our weapons as the VC. The VC were pretty much equipped with hand-me-downs. They'd take just about any functioning arm. The NVA were a trained military force, with better logistics, and tended to use Soviet arms pretty much exclusively.

After the '68 Tet Offensive, the VC ceased to exist as a combat arm.

[BillCA]

As I recall, the original M16 cartridge was manufactured using DuPont IMR extruded bar powders (4895 & 3031 IIRC). With this powder the M16 ran clean. At some point the powder was changed to a ball powder (Olin/Winchester) I think for various reasons (my memory is fuzzy here). The ball powder was easier to load and they were able to add more powder to up the velocity of the round.

Unfortunately, the ball powders caused secondary fouling problems. Late in the war it was determined that the calcium content in the ball powders was too high and that caused sticky extraction, gummed up the gas port & tube and lowering the reliability of a dirty weapon.

According to Speer, circa 1974, the original M16 had a 1:14 twist rate which DoD found didn't stablize the boattail military bullet sufficiently at long range so a 1:12 rate was adopted.

[Art Eatman]

There was an excellent article during the 1990s in Soldier of Fortune magazine about the whole political deal for the M16 and its ammo.

Yes, originally the cartridge used an IMR powder; the cyclic rate was designed for it at around 700 rounds per minute. Yes, Olin's political efforts led to the use of ball powder--which increased the rate of fire by around 200 rounds per minute.

I don't recall the details about the bullets; I remember there was some discussion of the two-projectile bullet.

I bought one of the first Mini-14s, whenever it was they first came out. Some guys I knew at Fort Hood through sports car stuff would occasionally "liberate" some "extra" 5.56 FMJ ammo. I noticed that at close range the bullet would blow up and fragment on jackrabbits. Say within 50 yards. Well, let me waffle a bit and say that the exit wounds resembled those from a Sierra 52-grain HPBT. Trying to find and examine the bullet leftovers was nowhere near being a priority...

Art

Art

[WhyteP38]

I still have a hard time believing the "blowing out intestines" from a shoulder hit statement, for the reasons I mentioned previously.

[CrazyLarry]

hitting a guy while running, in the back.....would mean you shot him while he was running away from you, much like the shot Tom Berenger pulls with a short burst in the movie platoon. why is it so hard for you to see a bullet tumbling down like this? anything else you need to nit pick?

[226]

No charging handle? You probably mean forward assist?

The owner then began to spout off how that is truly what the M16 is all about, no charging handle/brass deflector so it is truly light,...

[CrazyLarry]

yeah forward assist

[WhyteP38]

hitting a guy while running, in the back.....would mean you shot him while he was running away from you, much like the shot Tom Berenger pulls with a short burst in the movie platoon. why is it so hard for you to see a bullet tumbling down like this? anything else you need to nit pick?

It's not a nitpick. It's the only type of wound you referred to in your original post, and it's the only support offered for the thread's topic: the M-16's "unstable bullet." In fact, the rest of the post about crappy ammo is irrelevant to the topic, and the discussion of VC/NVA grabbing US weapons is a tangent.

Your original post said nothing about hitting a guy in the back while he was running away. It said "running." That could be someone running toward you, past you, or away from you. That's why I asked about the direction in my first post. However, now that you state it, I still don't understand how that particular type of hit caused that particular type of wound.

I'm not saying and have never said it didn't happen. I have said and am saying that I don't understand the dynamics involved, because it seems to me the bullet would have to do four things that, taken together, seem improbable:

1) A forward-moving 5.56 bullet enters the target's upper shoulder. Assuming relatively even ground between shooter and target, the bullet impacts either on a flat or--given the relative height differences between American and Vietnamese men--very slightly downward angle.

2) The previously forward-moving 5.56 bullet takes a drastic turn downward. Normally, I would expect the bullet to fragment, go through the shoulder, or lodge in the shoulder. But okay, let's say the bullet or a fragment of it moves downward at a roughly 45-degree angle (it may actually be a greater angle, but it shouldn't be less).

3a) It must traverse a path of about 14 inches through the shoulder joint, past the rib cage, and into the intestine area. It must somehow miss the shoulder joint--no mean feat given the hit in the upper shoulder--rib cage, both, or hit one or both. And that is assuming it misses the shoulder blade.

or

3b) If the 5.56 bullet hits the upper shoulder but does not travel internally, it must exit the shoulder and then somehow re-enter the target.

4a) A downward-deflected 5.56 bullet/fragment misses the shoulder joint and rib cage, reaches the intestine area, and changes direction again into a forward-moving bullet/fragment that has enough momentum to exit the lower abdomen and blow out the intestines.

or

4b) A downward-deflected 5.56 bullet/fragment hits either the shoulder joint, the rib cage, or both but powers through rather than deflecting, reaches the intestine area, and changes direction again into a forward-moving bullet/fragment that has enough momentum to exit the lower abdomen and blow out the intestines.

I have a hard time understanding how this could happen once, but since your original post stated "he told me of hitting guys [plural] running in the upper shoulder (entry) and then seeing the exit wound come out of their [plural] lower abdominal, blowing out intestines," this type of hit supposedly happened more than once. These dynamics seem remarkable to me.

[Art Eatman]

Well, bullets can hit bone and deflect; a major portion can wind up almost anywhere in a body.

One of Charles Whitman's bullets--granted, a 6mm Remington--hit a guy in the right shirt pocket. The bullet deflected off a rib, downward through the right lung and through the stomach into the intestines. At 420 yards.

Art

[Al Thompson]

I've witnessed via autopsy (on critters) bullets do strange things when bones are hit. You may not be aware that the intestines will protrude with just a small cut - seen that a time or two as well. :barf:

One of my platoon sgts was in the 173rd in "Nam and would agree with Crazy right down the line.

[CrazyLarry]

<Art Edit>

I asked Tom if he ever saw bullets coming in one place and exiting in another strange location, so he gave me that example from his personal experience. As I recall he claimed to have seen that happen twice, and then I didn't care to REALLY elaborate on it since as a vet he might no want to recall all of the people he may have killed at 530AM on a Sunday morning.

If the shooter had higher ground (maybe even flat?) I don't see any huge fallacy in his statements

[WhyteP38]

CrazyLarry:

I never claimed that Tom was wrong, nor did my tone ever get hostile as yours has become. I simply stated why I had a hard time believing the claim that you wrote, especially because your post was supposed to help quell a rumor but seemed--to me at least--built upon a rumor itself.

Given what Art Eatman and Al Thompson have written, I'd say Tom's claim is more credible in my eyes. Isn't that the purpose of these threads?

If you are going to post messages and expect everyone to agree with you, or that everyone will completely understand everything you write, I'm afraid you will end up disappointed.

<Art Edit>

[Demon5Romeo]

5.56 bullets can do some crazy things when they hit bone and tissue. I have heard the stories from Viet Nam about someone getting shot somewhere with a M16 and the bullet exiting in a totally different place. I always held these stories with a grain of salt until I deployed to Iraq for the first time.

Here are a couple of instance that I have seem firsthand on 5.56 bullets traveling a erratic path after hitting living tissue. I saw a guy get shot in the foot with a M249 SAW about 5 meters away. The bullet struck the bones in the ankle, turned 90 degrees, went up his lower leg shattering his shine bone, and came out sideways blowing out his knee cap. This was with M855 62 gr. Ball.

I saw a buddy of mine shoot an insurgent about 200 meters away with a M4 through the side. It hit a rib and the bullet exited his lower back, taking a kidney with it. Also with M855 62 gr. Ball.

In almost all the the shooting I have seen with 5.56 the bullet has either tumbled or fragmented if the ranges are 250 meters or less with an M4 or 450 meters or less with a M16A2 or M249. The wounds generally are pretty nasty. Once the bullet starts to tumble or fragment, it usually doesn't follow a straight path.

[WhyteP38]

Demon5Romeo:

Now we're talking apples to apples. It's always good to get info from an actual witness.

Sounds like you and your comrades-in-arms are doing good work over in "the world's largest kittybox." Stay safe and don't uncover any "t*rds" under the sand.

Your sig line mentions Saddam's kids. When a guy names his sons Uday and Qusay, I'm afraid to ask what he named his daughter.

[BigG]

As I recall from The Black Rifle, Gene Stoner specified 1:14 twist when they scaled down the AR10 to use the 222 Remington Special (early name of .223/5.56) which barely stabilized the bullet. Thus, it would dive and dart once it hit a semi solid medium, like flesh. The military (in its infinite wisdom) wanted cold weather accuracy for arctic conditions so the twist was quickened to 1:12, which brought accuracy up but the lethality down some.

[Warbow]

http://www.ammo-oracle.com/body.htm#twistduh

Q. If I increase spin or barrel twist, won't that decrease wounding by making a round more stable in tissue?

No.

[...]To describe how stable a given projectile is we use the gyroscopic stability factor (Sg). Generally you want a factor of 1.3 or greater for rifle rounds. 1.5-2.0 is a generally accepted value for 5.56 rounds.

For M193 the following variables apply:

axial moment of inertia (A) = 11.82 gm/mm2
transverse moment of inertia (B) = 77.45 gm/mm2
mass (m) = 3.53 grams
reference diameter (d) = 5.69 mm

Using the gyroscopic stability formula: Sg = A2 p2 / (4 B Ma) and assuming sea level we use an air density of 1.2250 kg/m^3 and discover that this this projectile will need on the order of 236,000 rpm for good stability (Sg > 1.3).

At 3200 fps M193 is typically spun up to more like 256,000 (1:9" twist) to 330,000 rpm (1:7") so that Sg approaches 1.9 or 2.0. 1:12" rifles will spin rounds at around 192,000 rpm and 1:14" rifles around 165,000 rpm. You can see why 1:14" rifles might have had trouble stabilizing M193 rounds.

Clever math types will see that density of the medium traversed (air in this case) has a dramatic effect on the spin required to maintain the Sg (density being in the first term's divisor). This is why cold conditions tend to dip "barely stable" rounds below the stability threshold. Without doing too much calculus it will be seen that an increase of three orders of magnitude (1000) in this variable will be a dramatic one for spin requirements. To balance things spin must be increased to compensate.

Through human flesh (which varies from 980 - 1100 kg/m^3 or about 1000 times the density of air) something on the order of 95,000,000 - 100,000,000 rpm is required to stabilize a projectile at speed. Given these differences it will be seen that the difference between a 1:12 or 1:14" twist when it hits flesh and a projectile launched from a 1:9 or 1:7" weapon is so small as to be beyond measuring. But the game isn't over yet.

[...]

In summary, and to take the most extreme case, a M193 projectile spinning at 350,000 rpm (from a 1:7" rifle) is going to upset in flesh (yaw) exactly as fast as one spinning at 150,000 rpm (from a 1:14" rifle). Claiming that twist rate has any impact on the speed of yaw and therefore terminal performance is just not in line with the laws of physics.

[davlandrum]

Warbow - now I know why I flunked physics.....my eyes melted just reading that....

[JR47]

Great, but the Arctic testing still revealed that the higher twist rates didn't stabilize the bullets sufficiently to give reasonable accuracy.

Using your math, the 1:14 twist may well have failed to stabilize the bullet enough to maintain in-line flight. At the distances used in jungle fighting, the bullet may already have begun to yaw/keyhole just as the average engagement range was reached.

I personally witnessed a SOG Team in which a member had taken his XM77, removed the flash supressor, and used a file to notch the crown. After replacing the flash supressor, he test-fired the weapon. It was wildly inaccurate at more than 25 yds. The bullets were key-holing at that distance. His experience had been that even these rounds were unpredictable in bullet path in flesh. More unpredictable than the issue ammo. I wouldn't recommend field-expedient testing of that sort, as it's not onlt your life on the line, but your buddy's as well. You see a lot of crazy crap at times like that.

[Harley Quinn]

If it took the body (human or other) to start the keyhole process?
If it is yawing and tumbling and shows on paper it surly can't be doing a good job for accurracy.
If you can't hit your target it has to be very depressing if you are being over run.
Sounds like they needed more hand grenades. Talk about fragmentation.

But you still need a good shooting rifle or pistol, if it gets there by chance it is going to take 3 times the ammo needed to get the job done.

HQ

[DPris]

Harley,
In shooting ARs & Mini-14s for a few years, I've never seen a 5.56 or a .223 bullet hit a paper target sideways. Admittedly, most of that has been with various commercial loads, but even in four years of qualifying with the original M16 I never saw anything but a perfect hole in the paper out to 100 yards.
I think it's important to understand the difference (and there is one) between the two types of "stabilization" as applied to the 5.56 round.
One refers to keeping it flying straight (in relative terms) in trajectory and following a predictable path/arc.
The other refers to what it does in living tissue.
Some twists and velocities may result in an erratic flight once the bullet gets out to a certain distance.
Bullet spin, velocity, and construction can affect what a bullet does once it encounters living tissue (along with the density & depth of that tissue).
You're absolutely right in saying that yawing in flight is not conducive to accuracy, but the M16 & variants are generally not considered to have an accuracy problem. The "problem" lies in what the bullet does (or does not do) when it arrives, rather than what it does in getting there.
That's what gives rise to the old saying among military gunnies that if you want a target rifle, get a 16, if you want a battle rifle get an AK.
Denis

[BUSTER51]

for any of the ladies that were offended by my delited reply on this subject I appoligize and will watch it in the future. 4 or 5 scotch's and I fell like it's the early 70's again.