It seems to me that that the primary advantage of the .223 is its ability to fragment at high speed. I just ran across this:

Gary K. Roberts did extensive testing of a wide variety of .223 loads in 10% gelatin, published in the July/August 1998 issue of Police Marksman (pp. 38 ff.). Some excerpts: Bare gelatin: Win 69 gr JHP-BT Match S223M Vel (avg) 2758 fps Ave penetration 11.9 inches Ave frag 74.6% Black Hills 75 gr JHP Match Vel (avg) 2580 fps Ave penetration 13.3 inches Ave frag 44.1% 9mm Fed 147 gr JHP 9MS [for comparison] Vel (avg) 1043 fps Ave penetration 13.2 inches Ave frag n/a Gelatin after passing through interior wall: Win 69 gr JHP-BT Match S223M Ave penetration 13.3 inches Ave frag 79.5% Black Hills 75 gr JHP Match Ave penetration 13.0 inches Ave frag 38.4% 9mm Fed 147 gr JHP 9MS [for comparison] Ave penetration 22.8 inches (!) Ave frag n/a The moral is, they don't penetrate any more than handgun bullets (at least heavy 9mm's), and are actually less penetrating after going through a wall, but a single wall won't stop them. Unfortunately, Roberts did not give data on any loads of less than 55 grains, due to a strong a priori bias against anything with less than 30 cm penetration. I would have liked to have seen the Federal 40-gr JHP data, particularly the wall test. Oh well.

Source

Quoted: Did you read the ammo oracle, the link to which is provided in the FAQ tacked at the top of this forum?

Yes, several times. Why do you ask?

Another site:

.223 Remington Ammunition for Personal Defense/Law Enforcement IWBA member Gary Roberts performed terminal performance testing of twenty-three different .223 Remington loads and published his results as follows: Roberts, GK: "The Wounding Effects of 5.56mm/.223 Law Enforcement General Purpose Shoulder Fired Carbines Compared With 12 Ga. Shotguns and Pistol Caliber Weapons using 10% Ordnance Gelatin as a Tissue Simulant." Wound Ballistics Review, 3(4); Autumn 1998, and Roberts, GK: "Law Enforcement General Purpose Shoulder Fired Weapons -- The Wounding Effects of 5.56mm/.223 Carbines Compared With 12 Ga. Shotguns and Pistol Caliber Weapons using 10% Ordnance Gelatin as a Tissue Simulant." Police Marksman, July/August 1998. As a result of his testing, Roberts recommended nine cartridges. Three of these cartridge recommendations are available only to law enforcement, whereas the remaining six are (or were) commercially available. We investigated the availability of these loads and offer the following commentary: Winchester Supreme Match 69gr JHPBT (S223M) was discontinued in 1998 and is no longer available. Federal 69gr JHP (223M) was tested and recommended by Roberts but we're unable to find any load under this product number in Federal's catalog. (We're unwilling to assume that the Federal .223 Remington 69gr JHP 223M cartridge, tested by Roberts, is the same as the currently available Gold Medal Match GM223M load.)  Attempts to contact Roberts for clarification were unsuccessful. Federal 55gr Tactical JSP (LE223T1) is available to law enforcement agencies only. This bullet produces the least amount of tissue disruption of all the .223 cartridges recommended by Roberts. The bullet does not fragment very much. Its performance is not much of an improvement over a .22 Long Rifle 40gr lead HP. Winchester 64gr JSP (Q3246 "Knurled") is a California Highway Patrol contract load which uses the 64gr Power-Point bullet with a cannelure. According to a Winchester spokesman, this load is also available to other law enforcement agencies upon request. The CHP specifies a cannelure to prevent bullet setback, and subsequent feeding failures, in its AR-15 rifles. Olin M855/Winchester 62gr FMJ (RA556M855) is from Winchester's Ranger line of law enforcement ammunition. Whether or not other manufacturer's M855/SS109-type ammunition delivers similar performance is unknown. Black Hills 60gr JSP, 68 grain JHP and 75gr JHP are recommended by Roberts. We contacted Black Hills ammunition company and confirmed that the cartridges tested by Roberts used the same bullets as current production ammunition. Olin M193/Winchester 55gr FMJ (X223R1) is recommended. This load is available as Winchester USA Q3131. Whether or not other manufacturer's M193-type ammunition delivers similar performance is unknown. Although Roberts tested Winchester's 64gr Power-Point JSP cartridge (X223R2), and found it acceptable, he did not specifically recommend its use in autoloading carbines and SMGs. There is no cannelure on the bullet, and Roberts alludes to feeding failures caused by bullet setback in the case mouth. In 1999 Winchester began offering a moly-coated 64gr Supreme Power-Point Plus load (SHV223R2), which develops slightly greater velocity than the 64gr Super-X Power-Point JSP load. Both the Supreme and Super-X loads use the same bullet. The critical minimum velocity for obtaining maximum terminal performance from .223 Remington/5.56mm ammunition is approximately 2700 fps. Bullets that are propelled below this velocity do not provide optimal terminal performance, and thus are less capable of creating wound trauma that will produce rapid incapacitation of a criminal attacker.

Source

I don't see what your concern is.  The test you originally put up there was twofold, to show the difference between bare naked and going through wall board.  And also that many .223 round are not any more dangerous as far as "overpenetration" as the handgun shown.  The cops are always talking about stray rounds and overpenetration and hitting innocent bystanders.  

What is your question?

From everything I have read, it appears that fragmentation is what makes the .223 so effective. A round can break in half and that is fragmentation. It seems that the .223 is so effective because of the "explosive" fragmentation. From what I have seen this occurs generally over 2900 fps. There have been some attempts to quantify it by % fragmentation. I am not sure how this is defined. Other than the report above, I have seen only one other attempt to quantify the amount of fragmentation:

www.bushmaster.com/le/tests/hornady_tactical_ammunition.htm

I find this interesting. The 40-60 gr rounds are plastic tip "Nosler style" rounds. The % fragmentation decreases with increasing weight and decreasing speed. 2910 fps was required for 75% fragmentation. The 75 gr round is a JHP-BT "Match style" and fragments much better - 72% at only 2616 fps.

This seems important. How is fragmentation % defined? Is the data available for various ammo at different velocities?

That statement was a lead into the posted data:

Black Hills 75 gr JHP Match Vel (avg) 2580 fps Ave penetration 13.3 inches Ave frag 44.1%

Black Hills is highly thought of here and elsewhere. Is this low fragmentation % not of concern?

That means 44% of that particular bullet fragmented.  That's not enough for you?  100% would be like if it all turned into more than 100 pieces.  At least this is how I've come to understand it.  10% fragmentation would still be more than a bullet that just yawed and didn't come apart.  From what I understand, the 75's have a threshold of 2200 fps or somewhere therein.  It's in the tacked thread and in the ammo oracle.  It is considered to be much more effective than M193 or M855 by any standard.  

Does this answer your question?  

I do not know what the ideal fragmentation % is. It seems that 75% would be ideal giving more fragmentation than 50% but still leaving 25% of the bullet for penetration.

I still do not know how it is defined. If the bullet breaks in half is this 50% fragmentation? My guess is that the fragments are weighed and compared to what is left of the main portion of the bullet.

I will read the ammo oracle yet once again as well as try to find the point in a tacked thread.

Thanks!

Quoted: I do not know what the ideal fragmentation % is. It seems that 75% would be ideal giving more fragmentation than 50% but still leaving 25% of the bullet for penetration.

The Nosler Partition has long been recognized as an excellent hunting bullet. I myself have used it for years.

The Nosler Partition is reported to usually retain approximately 60% of its original weight. I am unable to substantiate this from my own data because every Partition I have ever fired at game has had complete penetration on everything from 180 pound deer to 600+ elk.

Does 60% retained weight equal 40% fragmentation?

If so, it appears to be a proven approach.

viator

Fragmentation % is not solely what you judge ammo by.  Judge the permanant wound cavity size and location above all else. look at performance across a variety of velocities.  I would certainly appreciate it if you just asked questions instead of tossing out misinformed ideas untill you get a grasp on the fundamentals.  Fighting your misconceptions in other threads is tiresome. 69 grain ammo has a late yaw cycle and is far from ideal due to reduced effectiveness at reduced velocities and extended ranges.  Please quit trying to justify its superiority when it is inferior.

Tag for some later reading.