5.56mm vs. 7.62mm, An old argument but still valid

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Subject: 5.56mm vs. 7.62mm, An old argument but still valid
WFG 6/8/2004 6:06:17 PM

Given all the evidence from Vietnam that the 5.56mm round of the M16 was not adequate to stop even a small framed individual pumped up on adrenaline or dope; it seems that we are revisiting these issues again now in Iraq. Many operators in theater in Afghanistan and Iraq have made similar comments about the inability of the 5.56mm to stop and drop the current foe. Several have mentioned that a weapon like the M4 carbine, for its size and compactness, chambered in 7.62mm would be a great improvement. The conventional wisdom is that 5.56mm provides the operator with the ability to carry more rounds and that volume of fire is the preferred method of engagement. If it takes multiple hits to stop and drop your foe with 5.56mm then what?s the advantage. Fewer, more well aimed, and well placed shots with a round that is proven to stop and drop like the 7.62x51mm I think is the better choice. What are some of your thoughts?

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Nichevo 4/3/2010 12:42:41 AM

In my worthless opinion it is time for a new caliber. For several reasons:

1) The 5.56mm has the muzzle energy of a .44 magnum, and no doubt more at 100 yards. I don't think energy is the problem strictly speaking.

2) The 7.62mm is also not ideal. Its performance drops off over range and its bullet is not elegant.

3) Two calibers is too many.

I think we should have a single round somewhere between 6.5-7mm in caliber with a high ballistic coefficient and

enhanced terminal performance. Basically this means a longer bullet which is difficult to the extent that one is constrained by the 5.56mm round's dimensions. Either new propellants must be found to allow a shorter/shorter-fatter chamber, or abandon the limits of the 5.56mm OAL.

I also think more must be done with bullet lethality at any velocity. A flat-nosed round, perhaps, with a ballistic tip, designed to yaw/tumble or fragment rapidly upon impact in flesh while penetrating through hard targets. Game the Conventions somehow - German and Yug 7.62 rounds are known to have these characteristics so seemingly it can be done. I do think pistol rounds should be issued in a truncated cone design if we are confined to FMJs.

Afghanistan shows the need for a higher-powered rifle more than Iraq - in short, the distances. What is wanted is a single cartridge, for rifle or machine gun, which will do the job accurately and forcefully at long range.

Caseless or telescoping ammo is a nice idea, let's see when that works. I suppose telescoping solves for OAL.

If nothing else can be done, there needs to be found a new 5.56mm bullet design which will not make pinpricks at velocities under 2700fps. Comment please - do people here think a .223 hollowpoint (if allowed) would suffice?

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Mark_TX Battle Scenario:wounded enemies often better than dead 12/1/2010 4:18:23 PM

I used to develop weapons and analyze operational requirements for the US and other nations (mostly helicopter based weapons)

Weapon systems are judged by their ability to be "force multipliers". In other words, how much more effective force is brought to the battlefield with a particular weapon in a given scenario.

The scenario is essential to the equation, obviously, but the equation is not always as simple as "how fast can I kill bad guys, and how far away".

There are huge differences between US Army missions and say a US SWAT team. The biggest is that the US missions don't end with the battle and wars aren't won on the battlefield they are won when the enemy concededs it is not worth continuing and retreat from the theater, or go into deep hiding etc...

You may know this already, but a wounded comrade on the battlefield is a much bigger problem for the enemy than a dead comrade. Dead men don't cry, don't need treatment, and wounded men change the battle quicker than dead men.

When US soldier kills a terrorist, the enemy thanks Allah and the responsibility for his death belonged to the US.

When a US soldier wounds a terrorist, suddenly the responsibility for his death, if it happens, becomes that of his comrades.

I think the force multiplier for wounded enemies versus dead was something 7:1. Wounded really screw up things for days and days, chew up scarce medicines and resources and plkace huge demands on the morale of the enemy.

I suspect that was one of the largest factors in favor of the 5.56 vs 7.62 for military. That and logistics (weight, volume, cost etc etc) which is another big factor in weapon design.

SWAT, and police, need immediate authority over face to face scenarios. Very different from US Army. They need immediate stoppin power, at short range, with armor piercing, but not wall penetration. big rounds, fragmentary, etc...I'd guess they'd favor 7.62 but won't develop special purpose weapons themselves(?)

I haven't decided myself on M4 with 7.62mm but I'm leaning that way.

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Mark_TX Battle Scenario:wounded enemies often better than dead 12/1/2010 4:31:28 PM

"A-10 chambered for the 7.62"

Manufacturer? Also, see my post above re: pros cons of 5.556 v 7.62

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Machiavelli 12/1/2010 5:46:18 PM

I was in the army when we shifted from the 7,62 (German G-3, etc) to the 5,56 (Belgian FNC) my first reaction to the 5.56 was, is this a toy? But it made the life a bit easier, more ammo, easier handling and so on. The old G-3 called AK-4 here, but in basic the same weapon. It had a punch, but a very long weapon, to fire in auto was not an option at all. I only did that to test how it behaved in room clearing and similar small places.

I find these "new" calibers quite interesting, the 6.8 SPC and the 6,5, seems to be a mix of the advantages from both the 7,62 and the 5,56. I have never fired any of them, so I can only go with what other people are saying about them. The Barrett M468, later renamed to the REC7 and the Grendel for the 5,56. these two rounds can be used in SAW as well. I like the concept of them, which is the best of the 6,8 or the 6,5, I do not know.

take care

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Samuel H. Dighan 3/12/2011 1:37:09 PM

The 5.56 is to rifles and carbines what the 9mm is to handguns. Most LE have concluded 40 S&W to be superior to 9mm. The handgun debate is now on 45 ACP (stopping power) versus 40 S&W (capacity + power).

Regarding rifle rounds, I?d choose the 7.62×51 (.308) or x39 over 5.56 (.223) for a LE or home defence situation. If I had to worry about providing suppressing fire, weapon control while full-auto, AND humping around a full load for an entire day, 5.56 MIGHT win.

Army support logistics would need completely re-evaluated for squads w/ 7.62. Right now might not be a good time for that. However providing 7.62 (distance) and 12 gauge shotgun (house-to-house) to our troops would be optimal. The right tool for the right job every time is what they deserve, but improvise/adapt/overcome is the reality.

If the army were to go through that process, a modern 6.x (6.5, 6.65, 6.68) round would be an improvement over existing NATO choices. US SOCOM has developed the 6.8 Remington SPC. Armalite has an AR-15 chambered for 6.68, but a FN-FAL design would be superior (gas-piston).

See http://en.wikipedia.org/wiki/6.8_mm_Remington_SPC

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AThousandYoung 3/12/2011 4:31:07 PM

I think smaller bullets are more accurate due to higher velocity given equal amounts of powder. Is that true?

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Nichevo 3/21/2011 2:27:19 PM

You have to define your query more closely - I don't even know if you mean lighter weight or smaller caliber. If I had to answer as asked I would say no. Classically, IIRC, a heavier bullet is considered to be what is wanted for accuracy, but that's just other people's opinions. I am not aware of any correlation between muzzle velocity and accuracy.

What I do understand to be important to accuracy is stability of the bullet. This seems to be achieved mostly by black magic but one characteristic that correlates is ballistic coefficient, which is basically length divided by weight.

Basically a longer bullet in any caliber is best. And typically longer bullets means heavier bullets.

I'm talking out my tuchas, but at least I know it :>

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AThousandYoung 3/21/2011 11:22:15 PM

My reasoning is this. Same amount of powder means same amount of energy. Less mass means higher velocity. Less mass and higher velocity mean less bullet drop from gravity and less time for the target to move, or for something to get in the way - more immediate results when you pull the trigger and more of a straight path of flight.

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AThousandYoung 3/21/2011 11:26:51 PM

And of course the lesser recoil helps with accurate automatic fire.

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Nichevo Well lemme put it this way 3/22/2011 12:12:43 AM

Lemme put it this way. All pistol target ammo I am aware of is loaded light - heavy bullets light charges, sometimes hardly enough to cycle the action. Probably for the desirability of lower recoil, but also because the higher the velocity, the more any little imperfections on the nose of the bullet or any other such issues will make it deviate from true flight. You speak of hitting moving targets etc - this is what I mean, you have to define more carefully what does "accuracy" mean to you.

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