The AR-15: What You Should Know, by David Belk

Over on Talking Points Memo, a gentleman named David Belk, who's worked in hospital trauma departments, shared in comments there what he's learned about bullet damage in general and specifically the AR-15's capacity for damage.  He's granted permission for reposting elsewhere.  I think it's a damn good little essay on the subject, so I present it here:

The AR-15: What You Should Know

How is the AR-15 different from most hunting and sports rifles as well as a hand gun? There has been a lot of confusion and misinformation about this, so let’s first start with some facts about guns, bullets and what they can really do to you.

First: The most important thing to consider in assessing the damage caused by any projectile (like a bullet) is velocity. One of the first things I learned when I rotated through trauma surgery at Los Angeles County Hospital is the difference in the wounds caused by high velocity (greater than the speed of sound) versus low velocity (e.g. most hand gun) bullets. Low velocity bullets only damage the tissue they directly penetrate. For a low velocity (hand gun) shot to kill a person, it usually has to pierce a major artery or the heart. Often, when a person comes into an ER with a gunshot wound from such a gun, the protocol would be to check for bleeding or other signs of organ damage and, if none were found, send them home in about two days without any surgical intervention. Most people who are alive when they arrive in ER with such a wound would go home in under two weeks even if they needed surgery.

A high velocity bullet (usually from a high power rifle, high power hand gun at close range or a shot gun) damages tissue in three ways: direct penetration, shock wave damage to distant tissue and a brief, several centimeter wide, cavitary lesion that opens around the path of the bullet. This causes wide spread damage to organs and other tissue several centimeters in all directions from the path of the bullet. If a person is hit with a high velocity bullet anywhere in the head, neck or torso, he usually dies. If he lives, he’s almost guaranteed months of recovery in the ICU, usually on a ventilator, and then years of rehabilitation after (if he’s lucky). I’ve seen what just about any type of gun can do to a person so I know this from experience.

The AR-15 has a muzzle velocity of 975 meters/second- almost three times the speed of sound. That means that each bullet fired from an AR-15 has an extremely high kill potential. How is this different from a standard hunting rifle (like a 30-06), a shot gun or a high powered hand gun (a glock or .357 magnum)? After all, a 30-06 can kill a grizzly bear so imagine what it can do to you.

One of the main differences between the AR-15 and other high power guns is recoil (kick). Because it fires a small caliber (.223) bullet, the AR-15 delivers a very small (4-5 ft.lb.) kick with each shot. A nine year old child could easily handle the kick of an AR-15. A 30-06 or a 12 gauge shot gun has four to five times as much kick per shot. It could knock over an adult who is inexperienced with shooting guns. This is why it’s very hard to find magazines of more than about four rounds for semi-automatic hunting rifles or shot guns. They are very impractical. The same is true for most high power hand guns. You need a very strong wrist and a lot of experience to wield one effectively.

Guns like the AR-15 also generate a lot less heat per bullet fired (again because of the small caliber). These two factors (weak kick and less heat per bullet) greatly increase the number of bullets that can be safely and easily fired in under a minute. All of these factors together make the AR-15 a gun that was brilliantly designed to do exactly what it was intended to do: Kill large numbers of people in a small amount of time. A teenager with very little training can easily fire 20-30 extremely lethal shots in under a minute with an AR-15 equipped with a high capacity magazine.