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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    On a separate note,   3/26/2011 11:37:49 AM
What could we do with the 5.56 (or any bullet) to maximize effectiveness?
 
Can't legally go JHP,  soft-point, soft lead, right?  But how about a flat-nosed/truncated cone design, with or without ballistic tip, or even a nonexpanding hollowpoint, for more wounding/shock effect? 
 
This could be specifically for CQC, as such a bullet might fail at range.  Or possibly it might be a better brush-cutter, sandbag-chewer, windshield-puncher?

Now back to you, WarNerd. :>
 
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USN-MID       3/26/2011 3:15:57 PM

What could we do with the 5.56 (or any bullet) to maximize effectiveness?

 

Can't legally go JHP,  soft-point, soft lead, right?  But how about a flat-nosed/truncated cone design, with or without ballistic tip, or even a nonexpanding hollowpoint, for more wounding/shock effect? 


 

This could be specifically for CQC, as such a bullet might fail at range.  Or possibly it might be a better brush-cutter, sandbag-chewer, windshield-puncher?





Now back to you, WarNerd. :>

Already solved.
 
5.56 SOST.
 
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Nichevo       3/26/2011 7:00:16 PM
Yes, this seems to deal with windshields.  But will it add lethality or 'stopping power,' or just not glance off hard cover?  The open tip is tiny, though the (rigged-demo?) spent round is pretty nicely mushroomed.  (and wow, this passes Hague muster?!?) This bears little resemblance to the truncated cone ammo such as is now issued for the .45 ACP, which was more where I was going with the idea, or even SWC/Keith rounds.  Are we getting field reports of better results with this round?  Does the SOF community like it?
 
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Nichevo    Bump?   4/3/2011 4:10:34 PM
WarNerd?  Anyone?  I am not trying to make points, it seems an interesting topic to me.
 
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WarNerd       5/25/2011 11:44:13 PM

WarNerd?  Anyone?  I am not trying to make points, it seems an interesting topic to me.
Sorry, I was having a problem getting data I could trust for analysis, many of the online sources have dubiously powerful loads.  I finally remembered to borrow a copy of the Hornady Reloading guide when visiting my father.  These loads can probably be trusted.
 
One problem may be that the loads are arranged in 50ft/sec increments, this may explain a few inconsistencies, especially in the higher velocity to weight range.  Another is that barrel lengths used are the most popular and vary with the cartridge, which has a significant effect on best powder selection.  Some are also revolver cartridges (.357 Magnum and .44 Magnum), so there is even more variation.
 
General observations
All your choices were pistol cartridges. There is a substantial amount of unburned powder exiting the barrel in maximum performance loads which generally conceal advantages from slower powders, but interestingly in many case there are a choice of faster and slower powder loads providing equal performance, though the differences in powder speed is too small for solid conclusions. Also, as a consequence of the large quantity of unburned, rifle barrels, which are longer, cannot handle some pistol rounds. I found this when comparing performance of the .357 Magnum and .44 Magnum rounds which are considered dual use (pistol and carbine). The .357 was developed with dual use in mind, and the cartridge case capacity is limited to what would be acceptable for a fast burning (revolver ? 10.5?) powder in a longer barrel (carbine ? 16). The .44 Magnum was developed as a maximum capacity pistol cartridge (revolver ? 10.5?), and has to use a reduced load (approximately -10%) to be safe in the carbine (18?). Because of the dual use nature neither sets of loading data explored the use of slower powders in the carbine, and there are no similar cartridges used only for rifles.
 
Modern cartridges loadings are near the limits of chamber pressure.  Wildcat designs provide exceptions, but are not reliable. This is the reason why there can be sudden drops in performance for the heaviest bullets. Barrel twist may also put limits on maximum acceleration for the lighter bullets (the bullet jacket in the rifling shears off).
 
Cartridge volume is also frequently optimized for certain bullet, powder, and barrel lengths combination, limiting possible improvements unless the barrel length changes.
 
Changes in the .223 NATO have centered on improving long range performance at the expense of short range. It is also apparently possible to recover most of the performance loss from switching from the M-16 (20? barrel) to the shorter barrel (14.5?) of the M-4 (as demonstrated by at least on PDW proposal), but the resulting cartridge would pose problems when fired in the M-16 and M-249 machine gun.
 
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Sinvex    Reduced Lethality   8/17/2012 10:52:51 AM
Part of the reason that the 5.56 round was developed and used IS it's reduced lethality over 7.62mm round. The strategy behind this being that the resources consumed in treating wounded soldiers is greater than resource loss due to a fatality on the battlefield.
 
You not only have one less combatant on the field, but you also have others who are have to get him to safety, treat, and take care of him. This impacts the enemy in multiple ways including morale. 
 
This strategy may be applicable to a great many enemies, but in the current theater of engagement, or facing any enemy of a particularly radical zealous mindset it is counterproductive. You also have lethality drop off at a shorter range particularly with variants such as the M4 making it easier to engage from outside of your effective range while the enemy doesn't have that problem.
 
 
Given these factors I'm personally a fan of the 7.62 over the 5.56. Correct me if I'm wrong, just my two cents.  
 
 
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HeavyD       8/21/2012 2:41:55 PM
@Sinvex
 
In a previous comment I addressed this concept:  Against a regular army who cares about it's troops wounding can make sense.  Against extremists this does not make sense:  our troops need them down hard the first time.  
 
The .50 cal Beowulf round certainly accomplishes this when it hits it's target, but as most rounds are fired for suppression it's too damn heavy to hump required quantities.
 
Weight and recoil were the other two reasons for the 5.56 and 5.45mm rounds.
 
The foe of modern procurement is the desire for multiple missions with the same equipment.  Having the same round for the light machine gun and individual weapons seems to make sense but requires compromises that cause problems.  That said the Grendel round seems to be the sweet spot of lethality, range, weight and suitability for a LMG/SAW application.  6.5mm rounds have near-ideal sectional density for penetration and the Grendel is a short-action round unlike the NATO 7.62.
 
Let's just frikkin do it already.
 
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WarNerd       8/23/2012 4:32:56 PM
Part of the reason that the 5.56 round was developed and used IS it's reduced lethality over 7.62mm round. The strategy behind this being that the resources consumed in treating wounded soldiers is greater than resource loss due to a fatality on the battlefield.
 
You not only have one less combatant on the field, but you also have others who are have to get him to safety, treat, and take care of him. This impacts the enemy in multiple ways including morale. 
I believe this concept was first proposed by the British to push for the use of shrapnel rounds by their artillery. It was certainly used by McNamara’s ‘wiz-kids’ to justify the 5.56mm round to the public, but that is NOT why it was adopted in the end. And the round adopted was not the round that they were talking about.
 
The important factor on the battlefield is to incapacitate the enemy either by wounds or death so that he cannot continue fighting as quickly as possible. The factors that contribute to that are bullet placement and energy deposited in the target. You can divide bullet placement into 3 groups – vital (head, heart, etc. – quick death), bone (instant cripple, and the fragments slice through the tissue to cause massive bleeding), and flesh (everything else, often leaves target still active till it bleeds out). Up to 300m the 2 rounds are equal in effect for vital hits and bone, and the 5.56mm is superior for flesh because it keyholes quicker while the 7.62mm is too stable and tends to punch straight through creating wounds that bleed less. After 300m the the 7.62mm is ahead in because it still retains enough energy for bone, while the 5.56mm does not.
 
The question then becomes what kind of a fight do you expect? At ranges over 300mm the 7.62mm dominates, but the number of people who can hit something at that range is limited. Under 300m the 2 rounds are about equal, except that the 5.56mm user carries more than twice as rounds, a crucial advantage in combat. In close quarters battle under 25m the 5.56mm wins hands down – the more compact weapon is more maneuverable, the round adequate, easier to hold on target for repeat shots, and controllable in automatic fire (there is a joke about the 7.62mm at full auto goes ‘The first round is at his feet, the second in his belly, the 3rd in the head, the 4th over his head, and after that you are an antiaircraft gun.’).
 
The final factor is the training of the shooter. Prior to the Soviet invasion the Afghans were famous for their long range shooting capabilities. Since the invasion and shift from the Lee-Enfield to the AK-47 as the standard weapon for most tribal warriors they have lost this edge, and are little better than most 3rd world militias in term of accuracy. There are elite units in both the Taliban and al-Qaeda that are more accurate, and a number of mostly older Afghans that stuck to the old ways and serve as snipers, but their number are strictly limited. For most the rest long range shooting is a matter of spray-and-pray, or larger caliber support weapons not rifles. While there is a fair bit of ‘long distance’ fire from the enemy in Afghanistan, its average accuracy is very low as shown by the casualty figures.
This strategy may be applicable to a great many enemies, but in the current theater of engagement, or facing any enemy of a particularly radical zealous mindset it is counterproductive. You also have lethality drop off at a shorter range particularly with variants such as the M4 making it easier to engage from outside of your effective range while the enemy doesn't have that problem.
 
Given these factors I'm personally a fan of the 7.62 over the 5.56. Correct me if I'm wrong, just my two cents.  
You are right that a better cartridge is needed, but it is not the 7.62mm.
 
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Sinvex       8/24/2012 3:56:08 AM
 
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Sinvex       8/25/2012 6:44:31 AM
 
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