Why are the US forces still using the 5.56? I have no military background so I'm speaking from a civilian standpoint, but i feel like there are better calibers for standard issue? Is it because there is so much ammo? Is it really still a viable man stopper after having the bullets stabilized past design. Ar's originally were designed with 1:14 twist and now we are up to 1:7 for your standard run of the mill M4. which means your losing the erratic properties the bullet was supposed to have to bounce around in a human torso. They are sacrificing damage for accuracy, and I'd do the same. So why don't we use a cartridge that will give us that happy medium between damage and accuracy? Any thoughts or actual evidence to support would be helpful. Thanks

DH777

Balance between lethality and optimizing individual loadout .  Same reason USSR switched to 5.45

Basic reasons are the 5.56 gives a very flat shooting round that offers good lethality.
Since the round is so flat shooting, no sight adjustments are usually needed within normal combat ranges.
The smaller, lighter round allows a soldier to carry far more ammo.

Last, there isn't much around that's THAT much better that would justify spending billions of dollars in development and fielding of a new cartridge and a new or revised rifle to shoot it, along with the various machine guns and mini-guns that also shoot th 5.56.

The military has stated that they will not be buying a new rifle or type of ammo until there's a significant enough breakthrough in either to justify the expenditure to develop, buy, and field it.

In addition to the individual cartridge weight and budgetary concerns the two posters above mentioned, the 5.56 is that happy medium, or at least as close as we can get currently. With proper bullet selection, it works very well for the ranges and situations a rifle carrying soldier will likely encounter. It is a pretty potent cartridge with excellent terminal ballistics, and one can carry a lot of them. Crew-served weapons- MG's, mortars, rockets- and specialty weapons- sniper/anti-materiel rifles, grenade launcher, etc...- fill in the gaps. The 5.56 caliber rifle is one part in a larger system, and it works pretty well for now.

I don't know this for sure, but I thought the yawing has more to do with enough velocity.  I'm assuming that if a round is shooting at acceptable standards of accuracy and not keyholing, or wobbling overly much, it is stabilized.  But having said that, I'm not a scientist and maybe a less stabilized bullet will yaw more violently.  

I personally thought the 6.8 was a good idea.  However, I'm not convinced that the 5.56 is a bad GP round.  It certainly can be deadly.

As has been said, the stabilization has nothing to do with wounding power. Human tissue acts like a fluid orders of magnitude denser than air. Any bullet will destabilize when entering flesh.

The factors which affect wounding are speed and bullet design. The M855 was designed to be accurate to a decent range and to penetrate some body armor. This design, combined with lower velocity, makes it less effective at wounding. Long bullets like the Sierra 77gr OTM also require a faster twist, but are better at wounding than M193 at 1:12.

Long story short, the problem was going from a 20" barrel and easily fragmented round to a 14.5" or shorter and a round which prioritizes other characteristics. With decent ammo, even a short barreled AR will effectively incapacitate to several hundred yards.

I have to disagree with you on the stabilization not causing more/less damage. The whole purpose of the soviet 5.45 was for the bullet to become unstable and tumble. When this round was first put into use medics had no idea what was causing that much damage. It was practically dismembering body parts from what medical reports I read.

This about covers it.



 

Right around the turn of the 20th century smokeless powder was developed, and cartridges such as the 7x57, 7.92x57, 7.62x54 and .30-40 and .30-06 were developed.  The mindset behind these cartridges was they were all adequate for taking down a horse from underneath a cavalry soldier.  As automotive technology progressed, attacks by mounted horsemen was no  longer a concern however the cartridges remained in use.

After WWII, it was concluded that lighter, intermediate rifle cartridges fired from smaller, lighter carbines were also adequate against personnel, and that's where development of cartridges such as the 5.56 originated.  While European countries were pursuing a cartridge in the 6.8-7mm range, US firearms makers believed in a smaller caliber / higher velocity solution.  The civilian .222 Remington was the parent cartridge they started with, then experiment with extending the case length and neck size to meet their penetration requirements.

The 5.56 does not "bounced around in a human torso".

The 5.45 does not "dismember body parts".

You bring up the 5.45; do you know what twist rate of AK74?

1:200mm, or about 1:7.9"; which not materially different from the 1:7 twist uses in current M16 and M4 barrels.

If there is superior terminal effect to be expected of the 5.45 vs the 5.56, it is because of projectile design not twist rate.

Which makes sense as there are all manner of improved terminal effectiveness 5.56 loads available and the differences are in the projectiles.

I agree with this. OP you need to read more i'm afraid. The M16 was not designed with a 1/14 rifling but rather a 1/12 the 1/14 came about due to the machinery that colt had at the time. While this would often cause severe yawing and wounding the longer range accuracy was severely diminished by not properly stabilizing the round.

The round was never intended to tumble but was the result of a small caliber cartridge push by the military. The tumbling theory and "not designed to kill but injure to take two men out of the field" came about much later.

If you want to read up on something short and not terribly in depth then I suggest The M16 by Gordon Rottman for further reading I would highly suggest you read the Black Rifle by R.Blake Stevens.

Onto the 5.45 round. Much the same above the 5.45 round's ability to tumble or create vast wound channels has been exaggerated.  I don't have a link to the source but i'm sure you can find it. There were government tests conducted here to specifically test the yawing capabilities of the 5.45 and iirc they were shown to be no more severe than rounds of similar size.

Also for those that think the 5.45 is the wonder round that can rip off arms the ruskies had the same stopping power issues in Afghanistan that we have had with the 5.56. Many Spetnatz continued to carry 7.62x39 AK's for their superior penetration and large caliber as a result. So why not switch everything to a 7.62 short round? However in the venerable 7.62x39 round isn't great at range and isn't the most ballisticly (can't spell) efficient design.

Why is the 5.56 round still in service:

My 2 cents?

1) It is the standard round for many countries not just the USA, a lot of time and money has been sunk into standardizing mags, weapons and supply chains. It would be stupidly expensive to replace (not to mention politically irritating to many allies).
2) Many modern armed forces subscribe to a volume of fire theory which the 5.56 is quite capable of, being lightweight and low recoil allows you to carry a lot of ammo and put a lot of rounds on target with minimal fatigue.
3) It is a highly effective round in a good many situations.
4) There are no significantly better rounds out there....6.5, 6.8, 7.62. The right round depends on the situation and or war we are currently fighting.

The 5.56 is not great for long range engagements or punching through cover but for the time being it is the round in service and i don't see that changing any time soon.

also OP you seem to be confused by a bullet being unstable in flight and becoming unstable when it enters a medium denser than air. A bullet doesn't have to be unstable in flight to become unstable when it enters a body (i.e. bullets can be designed to tumble without having to use different rifling that could decrease accuracy).

I'm a little biased (for various reasons) but I do think there are better intermediate rounds out there countless studies have shown (The Brits after ww2, the SAW study, or the Chinese adopting the 5.8mm) that 6mm + is probably the "best" all around cartridge size....

BUT for the reasons listed above I don't think we will see a change for standard issues troops any time soon.



ONE LAST POINT (wall of text!!!) if you want an example of why the 5.56 won't be replaced any time soon take a look at how the 9mm replacement is going. NATO did their testing, decided the 5.7x28mm was better than 9mm and 4.6x30mm, then everyone got to bickering and now everything is stalled out.

I said it practically dismembers. The medical reports I read stated that it caused enough damage when a shot entered a thigh or upper arm to render the body part permanently inoperable. Requiring amputation.
Since you brought up bullet construction the 5.45 bullet that is put in the surplus ammo is specifically weighted to tumble when it's contacts anything. Comparing twist rate of both cartridges to say they're practically the same isn't gonna provide any correct answer. The cartridges are close in comparison but not close enough to say they'll perform equally. Hope I don't come across as rude. Sometimes that happens when we type I don't mean anything by it.

Thanks for all the comments thus far and pleas keep them coming ;)

Logistics (and intertia).  The same reason we didn't switch to .276 Pedersen in WWII.  What we have works well enough, and we (not to mention all of our allies) are committed to what we have.  We also have a lot of inventory and infrastructure to support it.

Nailed it.

The 5.45mm is not dismembering people; Practically or otherwise.

Afgan medics?

I suppose their relative lack medical technology had nothing to do with the high incidence of amputation for extremity wounds.

Yes, that is the point. Exactly.

Projectile construction determines terminal effectiveness.

Not rifling twist rate.

[/thread]

Lemme guess:

6.5?

6.8?

OP, no offense, but one of your first posts asks a question that has been posed at least 1000 times.

I would suggest doing some research instead of regurgitating tired gun myths.

Try starting here:  http://www.ar15.com/ammo/

ETA: if you have specific questions after reading up a bit, I'm sure you'll get better responses.

There's no need for a forum then. Every question has been asked before. Don't reply if you are tired of answering it. For your info I have searched and couldn't find exactly what I wanted. Sorry to waste your time

5.56 is cheap, it's light meaning you can carry a lot of it, and the power is adequate for typical combat engagement ranges.

We used to use big .30-cal rounds in the World Wars and it was determined those cartridges were too heavy, too expensive, and too much recoil when firing automatic, for the typical ranges actually encountered in real combat. No need for big expensive bullets that can go 600+ yards because most engagements aren't at that range.

I think you guys have summed it up fairly well. I've always thought a 243 would be awesome for a battle carbine. They know better than I do. It's a small fast bullet with the added punch. Thanks everyone

There's no need to replace 5.56, it kills adequately, and more importantly, you can carry a lot of it. Contrary to what many believe, rifles do very little killing. Mortars, artillery, bombs, crew serves and other more destructive items kill far more people than rifles do. It would be a waste of time and money to go to a different caliber, that would allow soldiers to carry less ammunition, and thus, have less ability to suppress enemies while waiting for more deadly weapons to come into play.

Furthermore, if you doubt 5.56's wounding potential, do a google image search for 5.56 wounds. It can produce some rather ghastly wounds, even with lower performance FMJ rounds. Many of the "I shot him 15 times and he didn't die" myths are just that...myths. Either the person telling it didn't actually hit the other person, or he hit them in a non-vital area; this isn't a fault of 5.56, no bullet is a magic pill of death.
I would also suggest reading some newer studies about twist rates, which have pretty well proven that the idea that 1:12 causes better terminal performance is false.

The vast majority of casualties are caused by Arty, CAS, then crew served weapons on the battle field. I would guess that even in the small-unit, infantry war of the GWOT (as opposed to the big armor battles such as Desert Storm) less than %10 of enemy casualties are caused by small arms fire. So statistically speaking, small arms are a very low priority for the Pentagon.

Thus, the bean counters in the Big Army, feel that 5.56 is "good enough".

I thought the 5.45 was designed with that little bit of air inbetween the tip and the lead on the inside, which allowed it to fragment a bit better.  Wasn't there a 5.56 out there that was similar?   Like Radway Green or something.  I realize the OTM bullets might behave a bit like this too.  

Also, just to clarify a point.  Yawing, as I understand it, has to do a lot with the base of a bullet being heavier than the nose, and when entering a medium that slows it down (as someone mentioned) physics demand that the heavier weight be switched to the front.  Like why you have more brake percentage on the front of your car.  Kind of...  although having the engine there probably has something to do with that too.

Quoted from above.
" Yawing, as I understand it, has to do a lot with the base of a bullet being heavier than the nose, and when entering a medium that slows it down (as someone mentioned) physics demand that the heavier weight be switched to the front."

This. 30-06 will yaw too given enough soft tissue depth to pass through. Physics my boy, physics.

The small air cavity at the tip of many match bullets and the like is not to induce fragmentation or peeling of the jacket, but to remove mass from the tip of the bullet, shifting the center of gravity toward the rear of the bullet and thus aiding ballistic stability.

I believe it was German DAG 7.62 NATO that had a really thin jacket and would fragment like none other.

That sub 3k round barrel life will be a hindrance. That won't even make it through a training evolution.

 


























 

Um... okay.

Winchester chromed the barrels of their WSSMs and they don't last 3k.
It's not "widening by 1" either, it's bullets sideways through the target or blowing up because the eroded bore cut them on the way down.

the only answer is logistics

 

That might be the one I was thinking of.  And thank you for further explaining what I was saying.  I don't have all the details correct and I apologize.  We do know that the OTM bullets fragment probably better than M193 or M855 at lower velocities.  But that might have to do with the actual thickness of the copper combined with the weight of it.  I suppose proportionally speaking.  But I wasn't sure if the OTM actually might have aided just a bit in fragmenting also.  Maybe not.

300Blk.....

Hump your 40 lbs of gear a few miles then get in a fire fight with 30 bad guys with  the basic load out of 7 mags. You'll wish your gear was lighter and will want more ammo. Most inexperienced people have no clue about what it takes.

Adopting a new ammunition that will not "drop-in" current configuration weapons requires much more consideration than simply what is (believed to be) "better". You have procurement issues, stock, supply and distribution issues. Can industry even gear up to produce the new ammunition on a time table that coincides with weapons replacement? How does this change affect our ability to operate effectively with our allies? You have training issues and you will have performance issues and growing pains that go along with the introduction of anything new. Cleaning kits, magazines, ammo carriers, spare parts, armory training, it goes on and on. It is no simple task.

On that note, 5.56 may not be the "best" round but it is a proven round and a known quantity.