Monday’s Numbers: A closer look at AR-15-style semi-automatic assault weapons and the grim details of what they do to human beings.

An individual fires an AR-15-style rifle at a shooting range in Greeley, Pennsylvania. (Photo by Spencer Platt/Getty Images)

The recent horrific mass shootings in Uvalde, Texas and Buffalo, New York have caused Americans to intensify their long-running national debate over so-called “assault weapons.”

In 1994, the federal government enacted a ban on the purchase of these firearms, which the US Department of Justice described at the time as “semi-automatic firearms with a large ammunition magazine that were designed and configured to fire fast and combat use. (Congress allowed the ban to expire in 2004, even though the ban was highly effective.)

Unlike an automatic weapon like a “machine gun,” largely banned in the US since the 1930s, that allows the shooter to simply hold down the trigger once and literally spray bullets, a semi-automatic rifle like the AR -15 and the like. it requires the shooter to repeatedly pull the trigger to fire each round.

That said, it would be inaccurate to imagine that such weapons in any way resemble the traditional image of a “rifle” that a layman might retain from, say, watching an old TV show or Western movie.

In a nutshell, as reflected in the image above, a semi-automatic rifle looks like the kind of weapon one might see in a theater of war or in an emergency involving a law enforcement SWAT team. Also, because the “mags” attached to these guns can hold dozens of rounds (i.e. bullets), a shooter can pull off numerous shots in a short time.

But what really sets these weapons apart from the guns many of us have seen on TV and in the movies is the damage they do. Most Americans grow up with the image of a soldier or criminal being shot, clutching his stomach or chest to cover the point of entry, then raising his hand to reveal a small red speck. We think about the trajectory of the bullet carved into the body that matches its diameter.

However, that is not often the case with assault weapons. As commentator Max McCoy explained last week in a powerful essay for the kansas searchlight:

The AR-15 is the civilian version of the fully automatic M-16, the standard American small arms since Vietnam. But the destructive capacity of the AR-15 is not in its fire mechanism, but in the ammunition that it uses. Both the AR-15 and M-16 use .223-caliber ammunition, with a bullet that is about the diameter of a pencil eraser. It is the same caliber size as a .22 long rifle cartridge, made for gunplay and squirrel shooting. But .223 ammunition has a larger, longer casing behind the bullet, with much more powder, pushing it at high velocity.

Eugene Stoner, the inventor of the AR-15, knew that a small bullet with a lot of power becomes unstable when it meets meat. Instead of making a clean wound, the .223 drops and eats its way through muscle and bone. So AR-15 ammunition is more lethal than a comparatively larger bullet. The smaller caliber also has a lighter recoil, allowing for more accurate shooting and allowing soldiers (or mass shooters) to carry three times as much ammunition for the same weight.”

A recent NPR report put it even more vividly:

Bullets from weapons such as handguns usually go straight through the target, medical experts say. By comparison, weapons like the AR-15s used in many mass shootings can liquefy organs due to their much higher projectile velocities.”

Some key relevant numbers about AR-15-style guns, the gun the National Rifle Association once infamously dubbed “America’s rifle”:

3 – number of times faster a bullet fired from an AR-15 style gun travels than one fired from an average 9mm pistol

3 – number of times more damage to a human body than a bullet fired from such a weapon typically inflicts

several inches – the width of the damage around its path caused by the bullet fired from an AR-15 style weapon through a process called “cavitation”

6-10 centimeters (or about the diameter of an orange) – the size of the common exit wound of an AR-15 bullet

only 5 – number of minutes it takes for a person shot with an assault weapon to bleed to death

As little as $400 – retail price of an AR-15 style gun

-37% – decline in US gun massacres during the 1994-2004 assault weapons ban compared to the previous decade

-43% – decrease in the number of people who die from massacres with weapons during that period

183% – amount by which gun massacres increased in the years after the ban expired

239% – amount by which gun massacre deaths increased

-70% – the risk of an American being killed in a mass shooting was 70% lower during the period the assault weapons ban was active compared to the 13-year periods before and after

20 million+ – number of assault-style weapons in the US today

two – number of distinctive green Converse sneakers that the parents of 10-year-old Maite Rodríguez were forced to rely on to identify her body after she was murdered in her Uvalde, Texas classroom; the weapon with which she was shot hurt her so much that she was unrecognizable.

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