M16\M4 Performance in Iraq

[Keith]

Never heard of that thing called recoil, have you stud?

Umm, my twelve year old enjoys shooting my FAL. If anyone can't handle the recoil of a modest round like the .308, they should be handling a typewriter in the rear instead of a rifle in the field.

I'm with Scout-sniper platoon, 2nd Bn, 24th Marines. We have a decidedly personal interest in this sort of thing,

And what do those combat experienced snipers say about the effects of a .308 round on an enemy combatant? Is there a big movement to replace the .30 caliber rifles with .223 sniper rifles?

No? And why not?

Keith

 

[tac17]

That larger diameter and mass also multiplies the effect of a hit on an exposed enemy. People shot with .308's are more prone to falling down and dying than people shot with .223's. To argue otherwise is... well, silly!

Silly huh? Ever heard of a thing called physics? In this remarkable thing called physics they discuss the fact that everything has an equal and opposite reaction. Does a .308 knock you down to shoot it? I will admit I have never been knocked down by a .308 rifle in my life, I am refering to bolt guns by the way, so you can't argue that the recoil system dampens the impact. If a .308 can't knock you down when you shoot it then a .308 projectile that was fired from said weapon can't knock you down either. So it can't be the actual impact of the bullet hitting them that causes them to go to the ground. So what is the mechanism that actually causes them to, fall down and die? As I posted earlier,

A spine shot would only incapacitate a determined human to a degree, it would depend on where the round struck the spine as to how much he would be incapacitated. A brain shot would be grand for an instant kill or incapacitation though, I hear it isn't the easiest thing to do when people are shooting at you. Everything else is going to involve them bleeding out, and it could take some time for their blood pressure to drop to a degree where they would be killed or incapacitated, barring a hit on a large artery or the heart itself.

A superficial hit with either one isn't going to be that effective. So tell me why someone that was hit with a .308 in the arm would be more likely to fall down and die than someone that was hit in the arm with a .223.

Does the hit on an exposed enemy make him mad or does it kill him?

That would depend on a great number of things that have little to do with which round you shot him with. It would depend a great deal on his mental state at the time of the shot. Was he upset, already adrenalized, or was he minding his own business when the shot hit? How does he think he is supposed to react when he is shot? All these things are rather important in the how effective any caliber is going to be unless you get one of those magic shots and take him out from the start. The effectiveness of any caliber is going to come down to where the shot hit and what tissues inside the body are no good anymore. I assure you that if you take a shot in the braincase or the heart at 200 yards from a .223 you aren't going to be thinking, " Boy I sure am glad he didn't hit me with a .308."

 

[Keith]

If a .308 can't knock you down when you shoot it then a .308 projectile that was fired from said weapon can't knock you down either

Why are you changing the subject? Did I say a .308 round would knock somebody down? Please indicate where I said this.

A superficial hit with either one isn't going to be that effective. So tell me why someone that was hit with a .308 in the arm would be more likely to fall down and die than someone that was hit in the arm with a .223.

Why are you changing the subject? Did I say that a .308 hit in the arm would cause someone to fall down and die? Please indicate where I said this.

The effectiveness of any caliber is going to come down to where the shot hit and what tissues inside the body are no good anymore.

Oh good, we are back on subject after your long rambling argument against things I never said in the first place.
A .308 round has triple the mass and 1/3 greater diameter than a .223. As such, simple physics dictates that it will penetrate deeper and make a bigger hole - meaning that more tissue is damaged. A .308 is also far more likely to penetrate any cover the enemy is hiding behind, again increasing the odds of a hit and the death of the enemy soldier. As you may know, people in firefights tend to hunker behind objects rather than standing in the open inviting chest hits.

Keith

 

[EchoSixMike]

Umm, my twelve year old enjoys shooting my FAL. If anyone can't handle the recoil of a modest round like the .308, they should be handling a typewriter in the rear instead of a rifle in the field.

Yep, and when I was 12 I was shooting at the National Matches at Camp Perry with an M14. And by the time I was 13 I had more firearms experience than 95% of active or reserve troops. Most troops DON'T get enough live fire to become proficient, you think that would be helped by going to 7.62x51, which by your own stats consumes 3 times the raw materials. The simple fact is that it's easier to train troops to shoot 5.56 than 7.62. When the DoD reinstitutes the DCM and the nation starts shooting as the national pastime in order to have a martially skilled culture, than maybe I could accept the 7.62x51 as a general issue cartridge. But since this is about as likely as an asteroid striking earth and killing us all, I won't hold my breath.

And what do those combat experienced snipers say about the effects of a .308 round on an enemy combatant? Is there a big movement to replace the .30 caliber rifles with .223 sniper rifles?
No? And why not?

Because sniper rifles are different critters than assault rifles. Although, to be frank, 90% of the shots made by snipers could be made by 5.56x45 rounds. And snipers get more rifle training than line grunts(although IMO they still don't get enough) And the USMC is fielding a 5.56x45 scoped rifle, the SAM(Squad Advanced Marksman) rifle, and it will likely be very effective because the bullets will go into the right spot to make the bad guys die.

I will say that the 308 with ideal bullets will be better than the 5.56 with ideal bullets, but that's not the arguement. The issued M80 7.62x51 is not better than the issued M855 or Mk262 Mod 1 5.56x45, and no arguement by you or I is going to change that simple fact. S/F...Ken M

 

[Keith]

Because sniper rifles are different critters than assault rifles.

We weren't discussing rifles, we were discussing bullets. It doesn't matter what rifle a bullet is launched from when it strikes the target.

The issued M80 7.62x51 is not better than the issued M855 or Mk262 Mod 1 5.56x45, and no arguement by you or I is going to change that simple fact.

Then I ask again, why don't military snipers use the .223? You simply don't want to admit that the .308 does more damage and penetrates intervening objects better than the .223.

If you want to argue that the M16/M4 is a better rifle/system than the FAL or M14 or whatever, for general combat conditions/logistics, etc, then that's a different argument entirely.

It may be that within the larger picture, wound lethality takes second place to other considerations like the amount of ammo that can be carried, etc. And that may be true, though if I was in a firefight I'd be hard to convince - I'd want a larger caliber vs more bullets!

Keith

 

[Jeff White]

Keith,

You said,

Umm, my twelve year old enjoys shooting my FAL. If anyone can't handle the recoil of a modest round like the .308, they should be handling a typewriter in the rear instead of a rifle in the field.

Does your FAL weigh 6 1/2 pounds? My M4 does. Don't you think a 6 1/2 pound 7.62x51 battle rifle might be a little hard for anyone to handle? How's your FAL do on full auto? Easy to control? One of the big reasons the 7.62x51 isn't general issue is that no one could build a rifle light enough that was controllable with full auto fire.

You ask;

Then I ask again, why don't military snipers use the .223? You simply don't want to admit that the .308 does more damage and penetrates intervening objects better than the .223.

First off, no one in the US military shoots .223 or .308. Yes, there is a difference between .223 and .308 and 5.56 and 7.62 mm. While they are for all intents and purposes interchangeable, they aren't the same rounds.

The reason military snipers use the 7.62x51 is that the 5.56x45 does not have the range for the mission. echosixmike is correct in that most military sniper engagements are close enough that the shot could have been made with 5.56x45mm. However, the sniper has an 800 - 1000 meter mission that can't be done with the 5.56x45 round. SOF snipers have had some very successful engagements with 5.56x45 SPRs shooting MK 262 mod 1 ammunition. The SPR is a specially built M16 from the NSW lab at Crane Indiana. Kills have been made at ranges that you would not believe possible with a 5.56mm weapon with this combination.

Snipers have a different mission then the basic rifleman. That's it, the reason they use 7.62x51.

It may be that within the larger picture, wound lethality takes second place to other considerations like the amount of ammo that can be carried, etc. And that may be true, though if I was in a firefight I'd be hard to convince - I'd want a larger caliber vs more bullets!

Go to Shawn Dodsons excellent Firearms Tactical Website. There is a link at TFL, don't know if there is one here or not. Once there, find the link to Dr. Fackler's work on military rifle rounds. You find, that both M193 and M855 have a better terminal effects then M80 ball. The 5.56x45 rounds break at the cannelure and fragment when they hit at velocities above 2500 fps. Not all 5.56x45 rounds exhibit this, just M193 and M855 and those bullets that are constructed identically. M80 ball which is the standard US 7.62x51 round does NOT fragment. It penetrates deeper before it yaws, then normally exits sideways. The wounds are not as severe as those caused by M193 or M855. There are 7.62x51 rounds that do fragment like M193 and M855, but they are not issued to the US military, IIRC the West German and Austrian 7.62x51 ball fragmented and gave similar terminal effects to the 5.56x45 loads.. It's not the caliber, it's the way the bullet is constructed. There have been on and off reports of lethality problems with current issue M855. M855 has a small air pocket between the jacket and the steel penetrator. There have been problems making the bullet with that air pocket from the start way back in the late 70s. My guess is that those problems may be related to production problems and some current M855 being not exactly to spec.

It's not quite as simple as bigger bullet equals bigger hole.

Jeff

 

[Blackhawk 6]

I have no doubt that the X-ray technician who provided the information that started this thread had nothing but the best intentions. Each of us can make his own conclusion regarding the an X-ray technician's qualification to comment on a particular round's suitability on the battlefield. But regardless of your conclusions about his qualification or the information he has provided, but compiling little snip-its of hear-say information to support your position in the great "5.56mm vs. 7.62mm" debate is ignorant, no matter which side you are on. I am sorry but there is no nice way to say it.

I can appreciate the fact that some of you do not consider the 5.56mm an adequate combat round. I respect your belief that the 7.62mm is a better choice for the standard infantry rifle. You are entitled to your opinions. But some of you are angry about this issue. Way too angry.

I commanded a rifle company in Afghanistan. My company saw 11 days of combat during Operation Anaconda and was involved in several other small operations. I have personally witnessed engagements with every standard weapon system available to a rifle company and some that are not. Not only did I not have any complaints with regard to weapons performance, but I did not hear any in our battalion.

The only complaint I heard about the M-4 was from a friend in 5th Special Forces Group whose complained that the M-4 was not putting people down fast enough at CQB ranges. At the same time, another member of 5th Special Forces Group had nothing but good things to say about his SPR and had made several kills past 600 meters with it. The first time I heard anything significant about the "poor performance" of the M-4 was when I returned to the United States and read it in... a gun magazine!

Additionally, I work with another officer who was a platoon leader in Somalia. He saw extensive combat, including 3-4 October, and he has no complaints about the 5.56mm. Several of his engangement were at 10 feet or less.

I am always interested in these type of threads because the subject interests me and in my current duty position I have access to all kinds of official reports and studies on a variety of topics. Hardly a day passes when I do not receive some type of after action review on either Operation Enduring Freedom or Operation Iraqi Freedom.

Keith, with all due respect, I was unable to recall any unit action that was halted because soldiers were unable to neutralize a threat with 5.56mm and an air strike had to be called in. Your assertion is suspect on a number of levels, but I do not claim to be the consummate expert on every engagement in Iraq. Please provide me the unit and location of the action and I will try to locate the after-action report. I will also post what is relevant.

All of that having been said, I think we can all agree that the 7.62mm is clearly superior to the 5.56mm in terms of external and terminal ballistics. But just because the 7.62mm is superior does not make the 5.56mm inadequate or a poor choice. Clearly there is room for improvement, but the American soldier/Marine is well-armed with his 5.56mm rifle. End of sermon.

 

[Sir Galahad]

I wonder if this argument raged between the British and French in the 1700s. "Well, of course a .69 caliber musket is better! You can carry 4 more paper cartridges than the .75!" "Awww, you don't know what you're talking about! Everyone knows the .75 has more knock-down power!" Then along came the .58 Springfield firing Minies. "Awww, what a POS! Everyone knows those conicals just zip right through a guy! You need a .69 round ball to anchor some Reb whacked out of his gourd on corn squeezin's!" Then came the .45/70. "Awww, what a POS! Everyone knows that you need at least a .58 Minie to anchor some Cheyenne wacked out of his gourd with peyote!" Then came the .30-40 Krag and later the .30-06 and some grizzled old guy was saying, "Awww, those little puny things are worthless next to a .45/70. Why, it's no wonder those Germans wacked out of their gourds on shnapps and sauerkraut aren't going down when hit with a .30-06! The .303 is even worse! I heard of a German who took a full 200 round belt from a Vickers water-cooled dead in the chest and kept right on cooking his bratwurst over a spent phosphorous shell! And the Germans themselves use a 8mm which is not much better. I read an article that said some American doughboy wacked out of his tin pan helmet on bourbon took a full 5 200 round belts from a Maxim and kept right on a-singin' "Over There!" so loud they could hear him a mile away even though both lungs were punctured!" Some Soviets were having a conversation about this. "Tovarich, every comrade knows this new 7.62x39mm is a POS. You need at least 7.62x54 to kill capitalists because every good communist knows they're all wacked out of their gourds on fervor to enslave the masses! And how do you plan to shoot enemies of the state with this puny round? You laugh now, but will you be laughing when those traitors come dancing out of the execution pit because of your ineffective 7.62x39? Then we waste pistol ammo having to shoot them in back of neck! We'll just see what Stalin has to say about this!"

 

[telomerase]

>"Tovarich, every comrade knows this new 7.62x39mm is a POS. You need at least 7.62x54 to kill capitalists

I've read that Hitler thought this way about the Sturmgewehr and its similar caliber (but 9mm was OK???)

Anyway, everyone knows the only way to get stopping power is with a microwave pulse big enough to vaporize the entire body.

 

[tac17]

Why are you changing the subject? Did I say a .308 round would knock somebody down? Please indicate where I said this.

I wasn't changing the subject you said:

People shot with .308's are more prone to falling down and dying than people shot with .223's.

So I explained to you the only mechanisms that would cause any round to cause anyone to fall down and die. In this debate it would not be due to the fact that an object with more mass impacted their body, not in the .308 versus .223 debate anyway.

Why are you changing the subject? Did I say that a .308 hit in the arm would cause someone to fall down and die? Please indicate where I said this.

Once again I wasn't changing the subject I was only pointing out that only good hits count so we could move on to the next line of though. Which was tissue damage that mattered and statements such as:

A .308 round has triple the mass and 1/3 greater diameter than a .223. As such, simple physics dictates that it will penetrate deeper and make a bigger hole - meaning that more tissue is damaged.

Once again you are incorrect in this assumption. If the 5.56 round enters a body within its range for fragmentation then it produces a much more devastating wound than does the 7.62, which merely enters into the body yawing rather deeply and then more than likely exits the body. You should keep in mind that the last rethinking of the M80 was in 50's I believe. The M80 hasn't benefited from any of the technological advances in bullet design over the last 50 years.

A .308 is also far more likely to penetrate any cover the enemy is hiding behind, again increasing the odds of a hit and the death of the enemy soldier.

I will agree with you as I always have that the .308 is more likely to penetrate some cover than the 5.56. On some cover it matters which caliber you are using and on some it doesn't. Like I have stated from the beginning they both have their strengths and weaknesses, the military obviously felt that the stengths of the 5.56 would better suit its needs than those of the 7.62.

 

[tac17]

I wonder if this argument raged between the British and French in the 1700s.

I am sure it played out about like you posted. I wonder if the negative reports we hear about some weapons are relative to something I heard someone say once. They said that the first time you fire your weapon in combat you aren't going to be that impressed with the results no matter what caliber it is. I wouldn't know personally, I have never fired a weapon in combat, but I can see their point. I guess you are just expecting so much more to happen, more of a movie type hit than you are going to get in real life.

 

[Sgt]

Good Grief !!

(Art was here...)

Sgt

 

[Art Eatman]

Ideas. We debate/discuss/debunk ideas.

Don't be in a hurry to respond to a post, as sometimes has seemed to be the case. Re-read the post before responding. Go off and drink a cuppa kawfee before re-reading your own post, before clicking on "Submit Reply".

, Art

 

[Sgt]

Gee Art,

I'm not sure if I should feel privileged, or violated?

 

[Keith]

Does your FAL weigh 6 1/2 pounds? My M4 does. Don't you think a 6 1/2 pound 7.62x51 battle rifle might be a little hard for anyone to handle?

Uh no, I don't. My hunting rifle is a six pound .350 Rem Mag. The .308 is a puppy dog of a cartridge, particularly in a auto-loader.

If the 5.56 round enters a body within its range for fragmentation then it produces a much more devastating wound than does the 7.62, which merely enters into the body yawing rather deeply and then more than likely exits the body.

If the 5.56 is designed to fragment, it will be a shock to all concerned. If the 7.62 exits the body, it's because it penetrated further and did more tissue damage.

Keith

 

[Keith]

Keith, with all due respect, I was unable to recall any unit action that was halted because soldiers were unable to neutralize a threat with 5.56mm and an air strike had to be called in. Your assertion is suspect on a number of levels

I'm quoting an official report posted right here on THR. I'm sorry I don't have a link, but the subject has been kicked around quite a bit here. Apparently, some Marine Recon units had guys equipped with M14's, while most didn't. Those that did, found they were very successful at neutralizing targets holding up the advance. Those that didn't found they had to call in air or artillery to do the same thing - and couldn't move as fast.

Most commonly, it was just a couple of armed guys in a cinder block building (the common construction method in the middle east). The .223 was completely ineffective against such buildings while the .308 was able to chew them up and clear them.

Keith

 

[natedog]

Dave, as much as I enjoy an unpolitically correct joke, and despise political correctness (control your speech, control your thoughts, control your actions), I said that only because it is apparent that there are many "fence-sitters" here who may be offended by jokes like that. It's the same reason that we aren't allowed to cuss in this forum. Also, your joke only perpetuates a stereotype that all gun-owners are a bunch of biggoted red-necks.

 

[tac17]

If the 5.56 is designed to fragment, it will be a shock to all concerned. If the 7.62 exits the body, it's because it penetrated further and did more tissue damage.

But aren't you wasting all the energy from that huge mass of the M80 round you were commenting on earlier if this occurs? I am speaking the facts on the subject according to the science published on the issue. Did you even take a look at those results I posted for you a few pages back?

I'm quoting an official report posted right here on THR. I'm sorry I don't have a link, but the subject has been kicked around quite a bit here. Apparently, some Marine Recon units had guys equipped with M14's, while most didn't.

Is this what you are talking about:
Excerpts taken from [url]http://www.2ndbn5thmar.com/oif/oifequipmentll.htm[/url].

"...M-4 carbine: Soldiers were very satisfied with this weapon. It performed well in a demanding environment especially given the rail system and accompanying sensors and optics. As one Brigade Commander said, "The M-4 with PEQ and PAC provided overmatch over our threat equipped with AK-47s and RPGs." The general consensus is that every rifleman wants the M-4 vice the M-16A2.
The most significant negative comment was reference the M-4's range. In the desert, there were times were soldiers needed to assault a building that may be 500+ meters distant across open terrain. They did not feel the M-4 provided effective fire at that range. The 82d Airborne soldiers wished they had deployed with M-14's at the squad level as the 101st did..."

I agree that could be a problem but it would depend on force structure I suppose. As I have stated numerous times so far both weapons have their strengths and their weaknesses. This would fall under the weakness heading for the 5.56 round. I honestly have no idea though whether a 7.62 rifle would have been that much help in that situation either. Does a 7.62 bullet still have enough gas to go through a cinder block structure at 500 yards? Perhaps a backyard experiment is in order.

 

[Keith]

But aren't you wasting all the energy from that huge mass of the M80 round you were commenting on earlier if this occurs?

The mass is only useful in that it destroys tissue. If a 7.62 goes through 24 inches of tissue, it's more destructive than a .223 which only penetrates say, 13 inches of tissue. It isn't about kinetic energy, it's about tissue damage. Ask a hunter about this.

And before you go off about how a human is only a foot thick or something, think about the fact the fact that humans in firefights are rarely standing up baring their chest for gun shots. They are prone or on hands and knees or crouched behind some sort of cover. If the bullet goes through the intervening object and then through as much tissue as it encounters, that's a good thing. If it goes through one enemy soldier and then hits the guy behind him, that's an even better thing!

Is this what you are talking about :

I don't know if that's the same report or not - probably is.

And I have no doubt that soldiers were pleased with the M4 vs the M16, but that's hardly the issue! no doubt I'd prefer an M4 over an M16 also.

What I found telling is where they discuss unit actions where an M14 was present at the company (or squad?) level and how that facilitated actions - and the recommendation that this option be explored further.

And that's probably the best we'll ever get. Something portable in .308 will (hopefully) end up in the hands of small units to be employed against light vehicles and structures. That would be a good thing.

Keith

And

 

[Jeff White]

Keith said,

Uh no, I don't. My hunting rifle is a six pound .350 Rem Mag. The .308 is a puppy dog of a cartridge, particularly in a auto-loader.

Hey bro, what's the cyclic rate of fire for that puppydog cartridge/rifle combo you've got there?

If the 5.56 is designed to fragment, it will be a shock to all concerned. If the 7.62 exits the body, it's because it penetrated further and did more tissue damage.

I doubt that the bullet was designed to fragment. No one knew enough about the terminal ballistics of any round to be designing bullets to fragment back then. It was a fortunate accident that the original M193 cartridge created such devastating wounds.

If the 7.62 bullet passes all the way through the body yawing 180 degrees and does not break up, how could it possibly do more tissue damage then a 5.56 that fragments? The science just doesn't back up your theory.

Please check out these diagrams:
http://www.firearmstactical.com/images/Wound Profiles/M193.jpg
http://www.firearmstactical.com/images/Wound Profiles/M855.jpg
http://www.firearmstactical.com/images/Wound Profiles/M80.jpg

You will note that both the M193 and M855 create larger permant wound cavities and disrupt more tissue. You can read Dr. Fackler's 1989 article on Patterns of Military Rifle Bullets published in the International Defense Review here:
http://www.fen-net.de/norbert.arnoldi/army/wound.html

Of course you have to be open minded enough to accept the fact that sometimes science will disprove some previously held notions.

Jeff

 

[tac17]

I don't think he put much stock in those diagrams when I posted them earlier.

 

[Keith]

Hey bro, what's the cyclic rate of fire for that puppydog cartridge/rifle combo you've got there?

Who cares? Issue them in semi-auto if full auto is too much.

Of course you have to be open minded enough to accept the fact that sometimes science will disprove some previously held notions.

I don't think you are open minded enough to accept science even when proven by your own links! The .308 punches through 64 centimeters, while the .223 punches through only half of that. In other words, if you shoot a crouching man in the butt with a .223 it stops in his abdomen. Shoot him with a 7.62, it comes out the top of his head. One is dead, one is still shooting at you.

Crouching man behind wall shot at with .223 - no hit. Behind wall with 7.62 - hit. In light vehicle - .223 - no hit. In light vehicle - 7.62 - hit.

Only hits count. And when hit, the longer the wound channel the more bones and tissue are destroyed. Forget all this temporary wound cavity baloney and look at actual DESTROYED tissues, nerves and bones.



Keith

 

[tac17]

...the longer the wound channel the more bones and tissue are destroyed. Forget all this temporary wound cavity baloney and look at actual DESTROYED tissues, nerves and bones.

It isn't just how long the wound channel is, it is also how big around it is as well. If you would consult the diagrams you would even see that the 5.56 rounds with fragmentation produces a larger permanent wound cavity than the M80 does. Penetration isn't the only thing you have to consider.

 

[Mike Irwin]

"In other words, if you shoot a crouching man in the butt with a .223 it stops in his abdomen. Shoot him with a 7.62, it comes out the top of his head. One is dead, one is still shooting at you."

If he was crouching with his a** towards you, he wasn't shooting at you in the first place. Unless, of course, he had the rifle point over his shoulder while looking in the opposite direction.


"Crouching man behind wall shot at with .223 - no hit. Behind wall with 7.62 - hit."

Just about every wall I've ever seen will defeat a 7.62 bullet if it's more than 1/2 a brick thick.

I've also shot my fair share of "light vehicles" with .223s through the body, etc.

Let's just say that I certainly wouldn't want to be in one when someone was shooting at it with either caliber. Ending up dead is a very distinct possibility.

At 90 yards the .223 military surplus I was shooting had no problem punching through the doors on an early 1960s junked Chevy pick up truck.

"Only hits count. And when hit, the longer the wound channel the more bones and tissue are destroyed."

Ok, we'll forget the temporary wound cavity. That's why I like the permanent wound cavity cut into ballistic gelatin by the .223 round over the much smaller and less destructive cavitiy cut by the .308 round.

 

[Jeff White]

Keith said,

Who cares? Issue them in semi-auto if full auto is too much.

Then we've just taken a great step backward to 1945. Full auto capability is very handy for a couple of things Infantrymen need to do i.e. gain fire superiority upon unexpected contact, break contact drills, final protective fires. Other then that hand held full auto is about useless. But why handicap our soldiers like that?

7.62 and 5.56 are very marginal rounds against light vehicles. You want to deal with vehicle mounted threats, you're getting into .50 BMG, MK19 40mm AGl, LAW and AT4 territory. I wouldn't want to depend on either 5.56mm or 7.62mm to stop an unarmored vehicle like the 60s era Chevy Mike references.
We fight as a combined arms team now. Even a light Infantry platoon is equipped with several weapons systems to give it depth and reach across the battlefield. And that light platoon can always count on at least 60mm mortar fires from the company mortar squad to supplement it's organic capabilites.

As Tac 17 mentions, the diagrams show the permanent wound cavities. You example of the crouching target is a bit humorous. Targets are fleeting and hard to see on the battlefield. Often you will fire at a terrain feature, treeline etc. Not at a nice "E' or "F" silhouette standing out against the skyline. I hate to think I'd have to find my enemy in that position just to get the most out of the terminal effects of the rounds I'm using.

Jeff