How Gun Blasts From Indoor Shooting May Cause Brain Injuries
The Times tested the blast waves of several popular civilian guns at an indoor range and found that repeated firing could add up to potentially harmful exposure.
Brain Blast
- Thread starter nm.otter
- Start date
Blowdowner
WKR
- Joined
- Jun 21, 2022
Someone please snippet the most telling sentence
A few highlights:
There are thousands of indoor ranges in the United States, and many have a similar layout: A row of lanes separated by bullet-resistant walls. Soft, shock-absorbent paneling is not standard and without it the booth can act like an echo chamber, reflecting more of the blast waves back toward the shooter.
“It’s one of those unspoken things,” he said. “You don’t realize that after a whole day of shooting, you have that ringing in your ears and that headache.”
Each blast creates waves of rapidly changing high and low pressure. The power of the blast is typically measured by recording the peak pressure of the biggest wave.
The U.S. military currently says that any blast wave that peaks below 4 P.S.I. is safe — though that guideline is not based on solid evidence, and will likely change as research progresses.
In The Times tests, sensors showed that the booth walls doubled the peak pressure for many guns, compared with shooting in the open. With a .357 magnum revolver, the peak pressure tripled.
The potential for harm from blasts is so poorly understood that even the U.S. military’s official safety threshold — 4 P.S.I. — is not based on real evidence. It’s only a place-holder, borrowed from decades-old guidelines for eardrum injuries. The military uses it because it doesn’t have the data yet to arrive at an evidence-based number for the brain.
The actual threshold for brain tissue damage may be much lower than 4 P.S.I. The Canadian military’s recommended safety threshold is 3 P.S.I. A U.S. Army study found symptoms of brain injury in grenade range instructors who were exposed to hundreds of blasts that measured less than 1 P.S.I.
It’s not clear how low the injury threshold might go. It’s not even clear that measuring peak pressure is the best way to gauge the risk.
The current military safety guideline looks only at a blast wave’s highest overpressure peak. But blast waves have dozens of peaks that can pulse through the brain in a few milliseconds.
There are thousands of indoor ranges in the United States, and many have a similar layout: A row of lanes separated by bullet-resistant walls. Soft, shock-absorbent paneling is not standard and without it the booth can act like an echo chamber, reflecting more of the blast waves back toward the shooter.
- The initial blast wave from firing a pistol takes only about 2.5 milliseconds to pass through the shooter’s body.
- Soon after, other waves that have bounced off hard surfaces come back toward the shooter’s head.
- Each time the shooter fires, the reflected waves converge, increasing the peak pressure.
- As the waves surge through brain tissue, they bounce off surfaces like the back of the skull.
- If the blast waves are strong enough, neurons can fray or break.
“It’s one of those unspoken things,” he said. “You don’t realize that after a whole day of shooting, you have that ringing in your ears and that headache.”
Each blast creates waves of rapidly changing high and low pressure. The power of the blast is typically measured by recording the peak pressure of the biggest wave.
The U.S. military currently says that any blast wave that peaks below 4 P.S.I. is safe — though that guideline is not based on solid evidence, and will likely change as research progresses.
In The Times tests, sensors showed that the booth walls doubled the peak pressure for many guns, compared with shooting in the open. With a .357 magnum revolver, the peak pressure tripled.
The potential for harm from blasts is so poorly understood that even the U.S. military’s official safety threshold — 4 P.S.I. — is not based on real evidence. It’s only a place-holder, borrowed from decades-old guidelines for eardrum injuries. The military uses it because it doesn’t have the data yet to arrive at an evidence-based number for the brain.
The actual threshold for brain tissue damage may be much lower than 4 P.S.I. The Canadian military’s recommended safety threshold is 3 P.S.I. A U.S. Army study found symptoms of brain injury in grenade range instructors who were exposed to hundreds of blasts that measured less than 1 P.S.I.
It’s not clear how low the injury threshold might go. It’s not even clear that measuring peak pressure is the best way to gauge the risk.
The current military safety guideline looks only at a blast wave’s highest overpressure peak. But blast waves have dozens of peaks that can pulse through the brain in a few milliseconds.
.50 BMG:
Increasingly, Army researchers believe that it may be just as important to calculate the total area of all those peaks — a measurement known as “positive impulse” — and then add up those measurements for every blast a person is exposed to in a day.
Single 5.56mm shot from an AR-15:
Based on the findings, the military is now considering whether to use a cumulative positive impulse exposure of 31.7 P.S.I.·milliseconds as part of a new daily safety limit. The potential new approach marks a stark change in how the military thinks about the hazard of blast waves. It is being reported here for the first time.
The Times measured an AR-15 rifle against that limit and found that while the peak overpressure of one shot was just 1.6 P.S.I., it took only 20 shots at an indoor range to exceed the proposed daily threshold for cumulative positive impulse. And it can happen fast.
That doesn’t necessarily mean that repeatedly firing an AR-15 rifle will cause a brain injury. But a lot is still unknown.
One of the Army’s lead blast exposure researchers, Walter Carr, said the military had largely focused on the short-term effects of large military weapons, such as artillery, and there had been almost no research on smaller-caliber guns like the AR-15.
A single AR-15 blast might be too small to cause damage, he said. But he cautioned that researchers have not answered that question, and still know little about the cumulative effects of months or years of firing rifles. In the absence of definitive data, he said, many people in the military are informally taking precautions to limit blast exposure whenever possible.
“We didn’t evolve with explosives surrounding us for a period of years,” Mr. Carr said. “It’s a very non-natural type of an exposure. It seems reasonable that there should be consequences.”
Increasingly, Army researchers believe that it may be just as important to calculate the total area of all those peaks — a measurement known as “positive impulse” — and then add up those measurements for every blast a person is exposed to in a day.
Single 5.56mm shot from an AR-15:
Based on the findings, the military is now considering whether to use a cumulative positive impulse exposure of 31.7 P.S.I.·milliseconds as part of a new daily safety limit. The potential new approach marks a stark change in how the military thinks about the hazard of blast waves. It is being reported here for the first time.
The Times measured an AR-15 rifle against that limit and found that while the peak overpressure of one shot was just 1.6 P.S.I., it took only 20 shots at an indoor range to exceed the proposed daily threshold for cumulative positive impulse. And it can happen fast.
That doesn’t necessarily mean that repeatedly firing an AR-15 rifle will cause a brain injury. But a lot is still unknown.
One of the Army’s lead blast exposure researchers, Walter Carr, said the military had largely focused on the short-term effects of large military weapons, such as artillery, and there had been almost no research on smaller-caliber guns like the AR-15.
A single AR-15 blast might be too small to cause damage, he said. But he cautioned that researchers have not answered that question, and still know little about the cumulative effects of months or years of firing rifles. In the absence of definitive data, he said, many people in the military are informally taking precautions to limit blast exposure whenever possible.
“We didn’t evolve with explosives surrounding us for a period of years,” Mr. Carr said. “It’s a very non-natural type of an exposure. It seems reasonable that there should be consequences.”
Fortunately, there are simple ways to limit exposure. The Times found that shooting in an open outdoor setting, rather than in an enclosed booth, can cut blast levels by more than half. When shooting indoors, ensuring that the gun barrel extends beyond the booth can reduce exposure. Choosing smaller caliber weapons and less powerful ammunition can also help.
Attaching a suppressor or blast regulator to the muzzle to direct the blast forward and away from the shooter can also make a big difference. In The Times testing, the blast from firing an AR-15 rifle indoors measured as high as 1.7 P.S.I. When a blast regulator was added, the measurement fell to less than 0.5 P.S.I.
Suppressors and regulators are often used by law enforcement and the military, but they’re pricey, and suppressors are tightly regulated in some states and illegal in others.
Lucas Botkin, who founded the popular firearms parts and accessories company T.Rex Arms and hosts a popular YouTube channel focused on shooting, said the concussive damage from shooting is a big reason muzzle devices like suppressors should be widely used.
“I know I’ve been messed up,” Mr. Botkin said. “And I have a bunch of buddies who are blasted just from shooting small arms for hundreds of thousands of rounds.”
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