I happened to look at some ballistics tables, and found that the .223 is one of the least powerful rifle rounds around.  The muzzle energy is around 1300 ft-lbs., vs 2000-3000 ft-lbs. for most other calibers.  Even the AK-47's 7.62x39 does around 1500 ft-lbs, and a .44 Magnum pistol reaches 1000 (though 9mm/.40/.45 tend to do only about 300-500).

Though the .223 is relatively high-velocity, there are faster rounds, such as .220 Swift, which also has a higher muzzle energy.  In any case, I don't understand why AR-15's are described as "high-power" when they seem to be one of the lowest-powered rifles around (aside from .22LR).

In light of this, I'm wondering why the .223 was chosen for the AR-15/M-16.  Is it the separation properties, low cost, reliability, or some other reasons?

"Knockdown power" doesn't kill.  Size and placement of the wound does.  The harder they hit, the better they will penetrate at longer distances.  This is vital for long range effective wounding.  Under 200 yds though, the .223 wounds better than the other FMJ variants of the rounds you named.  There are exceptions, like German and Swede 7.62x51, but generally the 5.56 wounds a lot better at most normal combat ranges than other rounds.

If you wound the enemy, it'll take three-men to care for him.

War is about winning - not killing.

The US would not adopt a rifle that had a hard time killing the enemy, however.

[url]http://groups.msn.com/TheMarylandAR15ShootersSite/problemswith556.msnw[/url]

[url]http://groups.msn.com/TheMarylandAR15ShootersSite/notdesignedforwounds.msnw[/url]

It all started with the ALCLAD studies.  The ALCLAD studies produced results that were very different then the military's thinking at the time.  1) nearly random shots during combat produced more casualties than aimed fire.  2) rifle shots were seldom beyond distances greater than 300 yards.  3) the majority of casualties from rifle fire were produced at ranges of 100 yards or less.  4) even expert marksmen could harldy make hits beyond 300 yards because of terrian or lack of cover.  Then the ALCLAD studies launched the SALVO studies.  Then the two studies caused the SPIW Program that was a horrible failure  During the SPIW tests the Army was experimenting with necked-down M1 Carbine rounds firing a .22 caliber bullet.  This proof that a .22 caliber bullet was effective caused the SPIW program to switch from shotgun type or single flechette rounds back to rifle rounds firing a 55 grain, .22 caliber  bullet.

Then Armalite heard of the tests and began to make plans to switch the AR-10 to a rifle firing a .22 caliber round.  The first AR15 used the AR-11's .222 Rem round.  Then the round was topped with a 55 grain boat-tail bullet made by Sierra Bullet Company, but there was a problem the case was not large enough and had to be redesigned, it was then designated the .222 Special.  Then the Remington made a round called the .222 Magnum, to avoid confusion (because both the .222 Magnum and Special could be fed and fired in the same rifle but the end results would be not to the users liking) they changed the name of the .222 Special to the .223 Rem.

Then the Army launched a search for a rifle firing a small caliber, it fell to the US Army Infantry Board for a Small caliber high velocity rifle.  The requirements were:
1. weight less than 6 pounds loaded
2. be capable of full-automatic fire
3. have a detachable 20 round magazine
4. have accuracy and trajectory equal or better than the M1 out to 500 yards

The round had to:
1. be able to penetrate armor, a steel helmet, a steel helmet, or a steel 10 gauge test plate out to 500 yards
2. be equal in lethality to the M1 Carbine within 500 yards.

The AR15's tested there showed great results but they were not accepted, but changes were made from the suggestions.  Then it was resubmitted to different tests and finally won out when the Air Force General helped to get it approved for tests.  

The information was taken from the book The Complete AR15/M16 Sourcebook by Duncan Long, its really a good book and I would suggest reading it.

It's light, you can carry alot more ammo.

Its not muzzle energy that offer stopping power.

Excellent information (accurate too) !!

I would only add that ArmaLite went fom the AR-11 and the .222 round due to the Army's changing the SCHV specs.  The result of those changes brought about the .223 and the AR-15

We have a member here "Gus" whose father did much if not all the development work on the new .223 cartridge.

read this:
[img]http://www.booktrail.com/Guns_Rifles/The%20Black%20Rifle.jpg[/img]

And dead fellow soldiers make other soldiers do heroic stuff.
GG

I must admit, a lot of the talk about the .223 being as adequate combat cartridge as the .308 seem to be more about rationalization than fact. I have no combat experience with either, but I have had a lot of experience in shooting and observing many varmint and big game animals shot with both the .223 (and other center fire .22 calibers) and the .308 and similar larger bores. Given bullets of similar design, there is just no comparison. And that is with no requirement to shoot through tree limbs, vehicles, walls, etc. My state and many others outlaw the .223 for big game, even those as small as white tail deer.

The .223 offers the combat soldier a substantial advantage in the amount of ammo that can be carried without weight penalty. It also came along at a time when the military training was (still is?) much more about firepower than either single shot marksmanship or power. I think the military has now figured out that full auto fire is largely wasted ammo, and perhaps there is some re-thinking of the power issue too.

Actually the military has known since the 1980's that giving full-auto weapons to the standard soldier is a waste.  In the early 1980's the Military JSSAP (Joint Services Small Arms Program) set about to make changes to the M16A1's currently in inventory.  Even before this was announced Colt already had began to make changes to the M16 rifle.  In Nov. 1981 50 new M16 PIP rifles where sent to Quantico, Virginia for tests.  Along with the changes was the burst mode replacing the full-auto selector position.  The M16 PIP was then adopted as the M16A2.  The only units to still have access to full-auto weapons are SF's which are special trained and need them because of their small unit tactics.

Power issues are not a major concern of the military.  The M16's 5.56x45mm round has time and time again proven itself.  Current reports from Iraq have shown this.  Members remember the report posted here about different equipment, weapons, etc. tested over there.

"5.56mm vs. 7.62 Lethality ~ 5.56mm “definitely answered the mail” and “as long as the shots were in the head or chest they went down” were typical quotes from several Marines; many who were previously very skeptical of 5.56mm ammunition. Most of the interviewed Marines who reported targets not going down and/or could still fight were referencing non-lethal shots to the extremities. There were reports of targets receiving shots in the vitals and not going down. These stories need not be described, but are of the rare superhuman occurrences that defy logic and caliber of round. Some Marines did ask about getting the heaver-grained 5.56mm rounds, up to 77 grain if possible."

The reports from the Delta Force and Rangers in the MOG are controversal about the M16/M4 and its 5.56mm round.  AgentFork posted a sight that was directly relating to this.

The only issue that would be related to the re-thinking of the power would be issuing the M14 rifles (most redesigned and improved) to the Designated Marksmen.  But still the are issuing the M16 or M4 to the ground soldiers and they are killing their fare share of enemy soldiers.

Also in 1962 the Department of Defense's Advanced Research Project Agency was conducting a project called AGILE.  AGILE was the attempt to find a better weapon for use in Vietnam.  One important result was this: A squad armed with AR15's firing the 5.56x45mm round had 5x's the kill potential compared to the M14 with its 7.62x51mm round.

Thanks to all...  Based on these reasons, it seems the .220 Swift could have been viable competition for the .223.  It's supposed to be the fastest round commercially available (reaching 4100 fps, as compared to 3100 fps for the .223), has a higher muzzle velocity, and is a bit lighter.  But it's also apparently expensive and tough on barrels.

HMMM - "Actually the military has known since the 1980's that giving full-auto weapons to the standard soldier is a waste. "  Sounds like a throwback to the pre-WWI days wheen they put magazine blocks on bolt guns to keep soldiers from firing out of their magazines and makin them fire single shot.

"High-Power" some folks use that referring to anything more powerful than a .22 rimfire, some make the differentiation higher or much higher.

I don't think many folks will disagree that the .308/30-06 family is a better cartridge for 500-900 yards in the hands of a trained rifleman, probably 300+ yards.  The services after WWII dropped the emphasis on long range riflery and went to a lmg for those longer ranges.  The vast majority of engagements are below 300 yards where the .223 is plenty sufficient and the .308 is at a relative disadvantage.  A ggod rifleman can hit what he can see with a .308 the .223 takes a very skilled rifleman to really reachout and touch beyond 500 yards.

In the current battle field those ranges (500-900 yards) are hardly to be expected.  From the same reports of the Marines in Iraq they are reporting engagements less than 300 yards as the normal.

"Enemy Engagements ~ Almost all interviewed stated all firefight engagements conducted with small arms (5.56mm guns) occurred in the twenty to thirty (20-30) meter range. Shots over 100m were rare. The maximum range was less than 300m. Of those interviewed, most sniper shots were taken at distances well under 300m, only one greater than 300m (608m during the day). After talking to the leadership from various sniper platoons and individuals, there was not enough confidence in the optical gear (Simrad or AN/PVS-10) to take a night shot under the given conditions at ranges over 300m. Most Marines agreed they would “push” a max range of 200m only."

The M16 was built around tests that never intended the rifle to shoot father than 500 yards.  But the M16A2 has the ability to engage a area target at 800 yards.

Go stand over there...I'll demonstrate.

I say this about any round. "Hey, stand over there, and do you want me to hold your sign?" [:D]