four times that. The pistol bullet speed is about 600 miles an hour, a little under the speed of sound while the AR is humming along at over 2000 miles an hour, close to 3 times the speed of sound. Much faster than the combat speed of the best fighter jets. The AR makes a sonic boom . . . inside the body. The shock wave created literally liquefies soft tissue.

It's designed to do that. The military has, at it's core, a very simple mission: tear things up and kill people. Anything the military orders has that as it base purpose. The AR-15 was developed to meet a Request for Quote from the Pentagon for a new infantry rifle.

It is made to kill people. Period.

Why is the 5.56mm round so deadly in school shootings?

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Flight ballistics: The bullet exits the muzzle of the AR-15 (or M4) unstable. The bullet is not merely spinning around its long axis (the front to rear line). It also "yaws" circularly, up to 4 degrees off center line (a form of gyroscopic precession). At about 100 meters, however, the yaw disappears and the round flies very stable out to about 400 meters, when it starts yawing again.

Victims of school shootings are all shot at ranges of much less than 100 meters. So the bullet strikes them while still yawing. That directly affects what happens to them,

Terminal, or wound, ballistics: ...
***
1. The 5.56 round exits the rifle at just more than 1,000 meters per second, about three times the speed of sound. When the 5.56 bullet hits a human body, it immediately begins to decelerate. This bullet's length to width ratio is high. The nose of the bullet begins to decelerate but the rear is still traveling supersonic. The rear is going faster than the nose. This causes the rear to overtake the nose, meaning that the bullet begins to tumble end over end. This tumbling in turn causes the bullet to fragment not quite completely and the fragments travel through flesh, bounce off bone into new directions and sever nervous system connections. This tumbling is greatly enhanced if the bullet is yawing at impact, as every bullet fired during a school shooting is. That is part one of what causes instant incapacitation.

2. Many ballisticians also say that the supersonic shock wave, shaped like a cone pointed in the direction the bullet was flying, enters the entrance wound and expands it rapidly for a distance into the body (how much depends on the location of the entrance wound and the angle). This causes excess bleeding over what the bullet would cause alone. This effect is called "hydrostatic shock," but not all armaments ballisticians agree that it is significantly damaging. In fact, while sound travels four times faster through human tissue than through the air, sonic waves have been proven not to damage the body.

Cavitation: Any high-velocity bullet (and almost all non-HV bullets, too) not only creates a cavity in the body corresponding to the width of the bullet, they also create large-diameter cavities from the sudden displacement of tissue caused by the speed of the bullet. This is called "cavitation." A radiologist who helped treat victims at Parkland described it this way:

***
more (pretty detailed, and gruesome): https://senseofevents.blogspot.com/2018/02/why-ar-15-is-very-deadly-military-weapon.html



I.e. every one of those white dots is a bullet fragment.

since repeal of the AWB. At about $750 per rifle more or less is a bucket load of $money$ the gun industry has made.
Its all about the money not the people the guns kill.. A quote that always sticks with me is...
"Are you for the kids? or are you for the killers?"
m

surgeon: The term "AR-15-style" is now used to refer to any rifle of that style. The original rifle was made for military use, but when the company failed to get buyers, it rebranded it for civilian use

Not sure about the above. Likely technically correct but a bit misleading. To clarify:
1 Armalite sold the rifle's design to another firearms manufacturer, Colt, in 1959. Four years later, the U.S. military selected Colt to manufacture a standard-issue model of the AR-15 — dubbed the M-16 — for soldiers in the Vietnam War.
2 The military had adopted the M14 by this stage, but they were forced to consider a request for a 5.56 cartridge [.223 and rifle just a year later in 1957. This was ArmaLite's AR-15 - the precursor to the M16.

.. these fast-moving [AR15} bullets essentially create shock waves in the body that cause tremendous damage to organs and tissue.

The shcok wave of the AR15 bullet is also known as cavitation, pressure exerted circularly/radially outward from the bullet path typically a couple inches in diameter from the bullet. Sounds awful but usually not, tho the author above is technically correct in that caviation can indeed cause tremendous damage to organs the closer the bullet path is to the organs. Thru tissue alone however, cavitation is generally not severe. If you were shot in the butt side to side, the cavitation thru the adipose (fat) tissue created by the bullet path could make you butt sore for a few weeks, but likely would not kill you, unless sepsis set in.

..shot with these [AR15] guns, the "destruction is much greater" than that caused by a handgun.

To me this warrants a 'duh'. A 22 caliber handgun bullet which generally causes the least wound damage of all bullets due its lighter weight, is essentially the same caliber as the AR15 bullet which is a 22.3 caliber bullet (known as a 223).

The differences between the 22 caliber handgun bullet & the AR15 22.3 caliber are as follows:
The 22 caliber bullet weighs between 30 and 40 grains. (29 gr for a 22 short rimfire, ~40 gr for a 22 long rimfire).
The AR15 22.3 caliber bullet weighs about 60 grains (from 55 to 62 last I heard)
The 22 caliber handgun bullet is a rimfire which takes milliseconds longer to spread result reduces explosive power compared to the AR15 bullet which is a center fire and is in a full metal jacket (fmj) shell casing resulting in rapid explosive spread & explosive power. Think of lighting a a 10 ft diameter circle of a gasoline spill from its center and then one from a side. The center will spread faster, same principle.
The 22 caliber handgun has a muzzle velocity of ~1,000 ft per second (fps). AR15 22.3 muzzle velocity ~3,000 fps.

Kinetic energy (KE) formula is KE = 1/2 x mass x velocity squared
22 caliber handgun bullet KE = 1/2 x 40 grains x 1,000 fps x 1,000 fps = 90 ft lbs
22.3 AR15 bullet: KE = 1/2 x 60 grains x 3,000 fps x 3,000 fps = 1200 ft lbs
The AR15 bullet has about 13 times more kinetic energy when it hits the target. An order of magnitude higher (10x).
Neat bullet energy calculator: https://www.larrywillis.com/bullet-energy.html

The primary reason for the AR15 bullets higher kinetic energy is its velocity, since 3k squared is 9m, while 1k squared is 1m, and 9 million is 9 times greater than 1 million.

The AR15 bullet also has (or at least had) a cannelure around it not quite at the middle, which is simply a light scoring slice around it which tends to enable the bullet to fragment into two as it hits a body, causing two bullet paths either of which can cause severe damage, and doubles the chance of this.

One main reason for the AR15 popularity is its light weight, as well as the light weight of its 223 bullets (~60 grain).

Compared with an AK47: .... AR-15 weighs 6.5 pounds in its stock condition, AK47 weighs 8.5 pounds.
... AR15 loaded 20 rds ~7 lbs; AK47 ~9.5 lbs. Other rifles with calibers over 30 caliber likely weigh more than an AK47 loaded.

Reason for larger loaded weight is that an AK47 bullet weighs 150 grains, the AR15 ~60 grains. More ammo can be carried at less weight, with the AR15, whether loaded or as ammunition backup.

What this lighter weight translates to is less recoil when the AR15 is fired, than an AK47 and larger caliber rifles.

AK-47 rifle recoil of 6.9 ft lbs... recoil for AR15 223 about 3ft lbs

Thus the AK47 has double the recoil energy of an AR15. Recoil causes 'rifle rise' where the rifle's muzzle end elevates when fired and needs be refocused on the target for better accuracy. With an AR15 the rifle can essentially be held in a fixed position by a shooter which enables him to fire more accurate rounds per minute than an AK47 or higher caliber rifles (some with much greater recoil).

Lightweight shooters generally prefer the AR15 since the light weight is easier on their arms and so much easier and faster to shoot accurately.

This recoil feature I did not see mentioned in the surgeons report.
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I support the current assault weapon ban, but let's face it friends, the horse are out of the barn. In 2004 when the clinton era assault weapon ban (awb) expired, the republican congress refused to renew it. In 2004 when the awb expired there were approx 400,000 assault rifles in America. Today, nearly 20 years later there are over 10 million assault rifles and some estimates at 15 million. The horse are out of the barn.
Enacting a new AWB will do little to curb mass shootings, altho perhaps have a marginal positive effect which would make it worth the while.

Although I support the death penalty ban in general, I think an expedited death penalty for school shooters and intentional mass shooters would do more to curb the awful 'new fad' the gun culture has created.
A fast track death penalty for killing kids in schools would mean a trial within 2 years - 3 years, eliminating legal maneuvers & delays, and stopping the death penalty being synonymous with 20 years free room and board where some portion are just as likely to die naturally in the prison.
A fast track death penalty for school shooters would not need a unanimous verdict but either 9 - 3 (preferably), then 10 - 2 or 11 -1. This would make some potential school shooters think twice if they were to get what they gave.
As it is, perverted shooters like nicholas cruz who recently was sentenced to life by a jury which voted 9 - 3 for the death penalty, they would get their just rewards for their unjust actions.
As it is and was, Cruz et al who get life rather than death penalty for mass murders, are REWARDED. REWARDED with free room and board for the rest of their lives. REWARDED with free medical and dental care for the rest of their lives. Free library privileges, free computers sometimes, they can even get a bachelors degree in some collegiate field. And this 'mental turmoil' which some say they will have to live with is mostly bunkum. The human mammal can self exonerate readily, create some inner sanctum where it was the devil made him do it then, it wasn't him it was something else inside him but now he's come back and is himself again and he's good now, gonna enjoy the rest of the life. Barf.
About the only thing the mass school shooter with a life sentence has to fear in prison, are his fellow inmates.