Yay, GUNS!

[rigney]

Timothy McVeigh (US Army, Oklahoma City Bombings)

Charles Whitman (US marines, Texas University tower shootings)

John Allen Muhammad (US Army, Beltway Sniper attacks)

Howard Unruh (WWII veteran, Camden NJ killing spree)

David Berkowitz (US Army, Son of Sam killer)

Arthur Shawcros (Vietnam veteran, Genesee River Killer).

....

Ahh well! You can't win 'em all. Edited July 27, 2012 by rigney

[swansont]

Timothy McVeigh (US Army, Oklahoma City Bombings)

Charles Whitman (US marines, Texas University tower shootings)

John Allen Muhammad (US Army, Beltway Sniper attacks)

Howard Unruh (WWII veteran, Camden NJ killing spree)

David Berkowitz (US Army, Son of Sam killer)

Arthur Shawcros (Vietnam veteran, Genesee River Killer).

....

 

and Nidal Malik Hasan (allegedly), who was in the army at the time.

[rigney]

and Nidal Malik Hasan (allegedly), who was in the army at the time.

And unless I miss my guess, all right wing nut cases? Edited July 27, 2012 by rigney

[Greg H.]

For the sake of discussion assume that there was a policeman in the theater equipped with a typical police sidearm .Would not the stopping power of one of those weapons be sufficient to prevent the shooter from continuing to aim and fire his own weapons? Also this fellow was not a trained soldier with knowledge of what to do when he himself comes under return fire.

 

While there is no "typical" police issue weapon in the US (each department buys whatever suits them), the most popular loads now seem to be 9mm, .40, and .45 ACP (source - various Wikipedia articles*). IIRC, someone earlier in this thread mentioned the attacker was suited up in a Type IIIA armor set, which is rated to protect against weapons of .357 and .44 Magnum rounds with a muzzle velocity under 1400 ft/s. (Personal Armor Performance Standards). A .45 ACP can achieve about 1220 ft/s of muzzle velocity(.45 ACP on Wiki), which means it's not going through the armor, unless you happen to get lucky and hit the guy in a weak spot.

 

 

*As a sample of the articles, see the following:

LAPD Service Weapons

NYPD Service Weapons

FBI Service Weapons

 

Edit to add a final source

Edited July 27, 2012 by Greg H.

[Arete]

And unless I miss my guess, all right wing nut cases?

 

Not sure if radical political motivation is a common thread but there is some research on military training being a precursor to serial killing/violent crime:

http://ijo.sagepub.com/content/46/4/453.short

http://books.google.com/books?hl=en&lr=&id=74-FPUCAG5oC&oi=fnd&pg=PA107&dq=military+training+mass+murder&ots=eMxe9RiNLn&sig=Re5RC-LGDRJU2oR64ExzSX0speQ#v=onepage&q=military%20training%20mass%20murder&f=false

http://www.tandfonline.com/doi/abs/10.1080/07393140220122662

[rigney]

Not sure if radical political motivation is a common thread but there is some research on military training being a precursor to serial killing/violent crime:

http://ijo.sagepub.com/content/46/4/453.short

http://books.google.com/books?hl=en&lr=&id=74-FPUCAG5oC&oi=fnd&pg=PA107&dq=military+training+mass+murder&ots=eMxe9RiNLn&sig=Re5RC-LGDRJU2oR64ExzSX0speQ#v=onepage&q=military%20training%20mass%20murder&f=false

http://www.tandfonline.com/doi/abs/10.1080/07393140220122662

Mayhaps! But here is a compiled list of nuts.

http://en.wikipedia.org/wiki/List_of_rampage_killers

[zapatos]

While there is no "typical" police issue weapon in the US (each department buys whatever suits them), the most popular loads now seem to be 9mm, .40, and .45 ACP (source - various Wikipedia articles*). IIRC, someone earlier in this thread mentioned the attacker was suited up in a Type IIIA armor set, which is rated to protect against weapons of .357 and .44 Magnum rounds with a muzzle velocity under 1400 ft/s. (Personal Armor Performance Standards). A .45 ACP can achieve about 1220 ft/s of muzzle velocity(.45 ACP on Wiki), which means it's not going through the armor, unless you happen to get lucky and hit the guy in a weak spot.

While it appears unlikely that a bullet would have penetrated his armor, to Bill's point, even if wearing armor I imagine that a shot to the head by a .45 would probably do a great deal to slow the shooter down.

[Greg H.]

While it appears unlikely that a bullet would have penetrated his armor, to Bill's point, even if wearing armor I imagine that a shot to the head by a .45 would probably do a great deal to slow the shooter down.

 

That depends entirely on the shooter's goal. In this case, his goal was (apparently) simply to shoot randomly into a crowd inflicting as much harm as possible. Distracting him isn't necessarily going to impact his "mission" because it's not based on any kind of precision. If his intended target gets missed, chances are high he still hits someone. The only real way to prevent him from inflicting more harm would be to put him down, at least long enough to incapacitate his ability to fire more rounds. You'd have more effect tackling him from behind, and pinning him down with sheer mass.

[mooeypoo]

And unless I miss my guess, all right wing nut cases?

 

Seeing how so far your guesses were mostly misses, how about we go with trying to figure out facts rather than tossing out infuriating guesses?

[rigney]

Seeing how so far your guesses were mostly misses, how about we go with trying to figure out facts rather than tossing out infuriating guesses?

Infuriating guesses? Wow! Do I detect a bit of animosity? Edited July 27, 2012 by rigney

[zapatos]

That depends entirely on the shooter's goal. In this case, his goal was (apparently) simply to shoot randomly into a crowd inflicting as much harm as possible. Distracting him isn't necessarily going to impact his "mission" because it's not based on any kind of precision. If his intended target gets missed, chances are high he still hits someone. The only real way to prevent him from inflicting more harm would be to put him down, at least long enough to incapacitate his ability to fire more rounds. You'd have more effect tackling him from behind, and pinning him down with sheer mass.

I don't know the physics behind this so I am only guessing and basing this on personal experience, but wouldn't a .45 to the head be more than a distraction? I've had my head knocked many times by hitting the ground, hitting somone's fist with my nose, a baseball to my helmet, and others. I was knocked unconscious once and was disoriented several times. Would a bullet to the head have a similar impact as a baseball to a helmet?

[mooeypoo]

Infuriating guesses? Wow! Do I detect a bit of animosity?

 

Not at all, it's just very frustrating when you seem to toss very "extreme" type claims into the mix without checking them first.

We're trying to have this discussion as emotion-clear as possible and as rationally as possible, and those don't help.

 

I don't know the physics behind this so I am only guessing and basing this on personal experience, but wouldn't a .45 to the head be more than a distraction? I've had my head knocked many times by hitting the ground, hitting somone's fist with my nose, a baseball to my helmet, and others. I was knocked unconscious once and was disoriented several times. Would a bullet to the head have a similar impact as a baseball to a helmet?

If it's from the front, it can be the killer. I don't think a gas mask and goggles stop that bullet. I think we might be underestimating how good you might need to be (and stable) in this situation to actually aim and shoot that relatively small space, while he's moving, and while you're surrounded by panicked injured people and tear gas.

 

But I think that if anyone COULD make that head-shot to the front, it would be the killer. To the back, I'm not sure, but it would likely be a great distraction... it would probably get him to pause for a bit, enough to maybe jump him.

 

BTW, we can calculate that quite easily. Anyone knows what speed a .45 travels with as it goes out of the barrel? I'm not sure. If we know that, and estimate the distance, it's possible to calculate the force it would impact on the helmet and see if it's enough for some significant trauma.

[rigney]

I don't know the physics behind this so I am only guessing and basing this on personal experience, but wouldn't a .45 to the head be more than a distraction? I've had my head knocked many times by hitting the ground, hitting somone's fist with my nose, a baseball to my helmet, and others. I was knocked unconscious once and was disoriented several times. Would a bullet to the head have a similar impact as a baseball to a helmet?

Perhaps even a .22 cal. may have been a deterrant if done right. But time and an understanding of what is happening is critical. You are at the movie to see a flick, not to witness mass murder. We will never know what might have been even had everyone been unarmed or fully armed??. Go see this guy and be prepared for Armageddon #3, should it come to your local theater..

http://biggeekdad.com/2011/10/kellers-riverside-store/

[iNow]

Back to the question in the OP, a good article from Fareed Zakaria:

 

http://globalpublicsquare.blogs.cnn.com/2012/07/27/time-to-face-facts-on-gun-control/

 

We have 5 percent of the world's population and 50 percent of the guns.

 

But the sheer number of guns isn’t an isolated statistic. The data shows we compare badly on fatalities, too. The U.S has three gun homicides per 100,000 people. That’s four times as many as Switzerland, ten times as many as India, 20 times as many as Australia and England.

 

Whatever you think of gun rights and gun control, the numbers don’t flatter America.

 

I saw an interesting graph in The Atlantic magazine recently. A spectrum shows the number of gun-related deaths by state. Now if you add one more piece of data – gun control restrictions – you see that the states with at least one firearm law (such as an assault weapons ban or trigger locks) tend to be the states with fewer gun-related deaths.

 

<...>

 

I've shown you data comparing countries, and comparing states. Now consider the U.S. over time. Americans tend to think the U.S. is getting more violent. In a recent Gallup survey, 68 percent said there’s more crime in the U.S. than there was a year ago. Well, here’s what I found surprising: the U.S. is actually getting safer. In the decade since the year 2000, violent crime rates fell by 20 percent; aggravated assault by 22 percent; motor vehicle theft by 42 percent; murder – by all weapons – by 13 percent.

 

But guns are the exception. Gun homicide rates haven’t improved at all. They were at roughly the same levels in 2009 as they were in 2000. Meanwhile, serious but non-fatal gun injuries caused during assault have actually increased in the last decade by 20 percent, as guns laws have gotten looser and getting automatic weapons has become easier.

[Greg H.]

BTW, we can calculate that quite easily. Anyone knows what speed a .45 travels with as it goes out of the barrel? I'm not sure. If we know that, and estimate the distance, it's possible to calculate the force it would impact on the helmet and see if it's enough for some significant trauma.

 

The number I found was 1220 feet/second on the high end for .45 ACP and a low end of about 900 f/s.

[mooeypoo]

The number I found was 1220 feet/second on the high end for .45 ACP and a low end of about 900 f/s.

 

Okay, so assuming air friction is too marginal to affect the bullet on these distances (a few meters to a couple of dozens of meters) we will assume the bullet hit the helmet at that initial speed.

 

For convenience, I switched units to meters per second. Also, just for the sake of argument (and also since this too would likely be rather marginal) I am ignoring downwards force, and am assuming a perfectly horizontal trajectory.

 

That would mean the bullet would hit the helmet at velocity of 1220 feet/second = 371.856 m/s

 

We will assume the tactical helmet stopped the bullet (otherwise there's no point anyways to this discussion since the guy would be dead). I will also assume it stopped the bullet as "far" as it could go, so I'll take about 1 cm travel distance until the bullet stopped assuming it got embedded in the helmet.

 

(It's been a while since I did these, verify I didn't miscalculate anything here)

[math]v_0=371.586 \text{ m/s}[/math]

[math]v_f=0 \text{ m/s (complete stop)}[/math]

 

[math]x = 0.01 \text{ m}[/math]

 

I'll use this equation -

 

[math]v_f^2 = v_0^2 + 2a(x_f-x_0)[/math]

 

Rearranged to this:

 

[math]a = \frac{v_f^2 - v_0^2}{2(x_f-x_0)} = \frac{0 - 371.586^2}{2(0.01)} [/math]

 

[math]= \frac{-138076}{0.02} = -6903800 \text{m}/s^2[/math]

 

So, assuming mass of a bullet as 15g

 

[math] F=m*a = 0.015\text{kg}*( -6903800 \text{m}/s^2) = -103557 N = -103 KN[/math]

 

I'm not sure how much force is needed to cause a concussion. Also, we should take into account that helmets (especially tactical helmets) are especially designed to absorb the majority of this force, so the head will NOT experience this amount. How much do they absorb? no clue, but even things like motorcycle helmets can save a head from an injury that would otherwise break the skull, so I would guess it's quite a significant amount..

 

Someone will have to pick it up from here, since I am not too sure what to compare this force to.

 

~mooey

[Joatmon]

Mooeypoo - seems you are giving yourself more of a headache than the person wearing the helmet!

Edited July 27, 2012 by Joatmon

[mooeypoo]

Well, we *are* a science forum. Might as well do some back-of-napkin calculations when talking about something sciencey

[zapatos]

I'm having a hard time finding anything specific but I did find this comment:

Be aware that your head is much more susceptible to blunt trauma than your body. ANY impact of a bullet on a helmet WILL CAUSE INJURY AND CAN CAUSE DEATH. You put the odds more in your favor with head protection, but, just as with ANY armor, no guarantee of invulnerability can be made.

http://www.bulletproofme.com/Ballistic_Protection_Levels.shtml#No_Vest_Bullet-PROOF

[CharonY]

Hmm according to helmet websites they appears that helmets are certified according to head acceleration upon non-ballistic impact. 200 Gs appears to be the generally accepted. It appears that they are dropped from a given height. I have not found the standardized test info after a quick search, though (must be listed somewhere).

But that is unlikely to be easily translatable as the impact area of a bullet is quite different.

Edited July 28, 2012 by CharonY

[Greg H.]

So, assuming mass of a bullet as 15g

 

[math] F=m*a = 0.015\text{kg}*( -6903800 \text{m}/s^2) = -103557 N = -103 KN[/math]

 

I'm not sure how much force is needed to cause a concussion. Also, we should take into account that helmets (especially tactical helmets) are especially designed to absorb the majority of this force, so the head will NOT experience this amount. How much do they absorb? no clue, but even things like motorcycle helmets can save a head from an injury that would otherwise break the skull, so I would guess it's quite a significant amount..

 

Someone will have to pick it up from here, since I am not too sure what to compare this force to.

 

~mooey

 

Yeah, no clue, but that's going to ring his bell, that's for sure. It might be enough to daze him, depending on how much the helmet can absorb.

 

Edit: And that's assuming the helmet he was using was designed to small "point" intrusions like a bullet, rather than wide area crushing (such as a motorcycle or sports helmet). Assuming he's using a bog-standard military Kevlar helmet, they're rated up to 1600 ft/sec (according to http://www.compassar...ion-helmets.htm), but that doesn't give us any information on how much of the force transfers to the skull. I'm going to dig a bit and see what I can find.

 

Edit 2: Mooey, I did find some numbers that might require you to redo some calculations. According to http://www.operation...rg/helmets.html:

In ballistic testing, while the helmets will stop a 9mm round, the impact indents the helmet approximately 1.5. inches. If the helmet were against the skull when the bullet strikes, that indentation is transferred to the skull with resultant injury and/or fracture. Holding the helmet permanently off the skull with shock-absorbing pads reduces or eliminates that scenario.

 

So the bullet will actually travel closer to 3.8 cm before it stops - the strap suspension in the helmet keeps the dimple from smacking the skull full force. Some quick napkin math shows that reduces the force down to about 27 kN.

And yet another edit

According to Wikipedia, the threshold for a concussion in sports medicine is around 70-75 g's of acceleration. Can we convert the kN to g-force?

Edited July 28, 2012 by Greg H.

[Cap'n Refsmmat]

A head is about 5 kg, so by F = ma, the acceleration caused by 27 kN is about 5400 m/s², or 551 g. This would not be very good for your head.

[Greg H.]

A head is about 5 kg, so by F = ma, the acceleration caused by 27 kN is about 5400 m/s², or 551 g. This would not be very good for your head.

 

Cheers Cap'n.

So, that's how much it would accelerate the helmet. How much it accelerated the actual skull would depend on the padding and the web suspension. But no, that's definitely not going to be nice to your brain.

[Iggy]

I think people in the US, on average, are more willing to assume the risk of liberal gun laws. On a scale between a statistically safer country, and a country which gives one the trouble of self-reliance, we do often want to push the scale toward the risks and responsibilities of self-reliance. I confess feeling a mushy sense of dignity at Jefferson's... "The man who would choose security over freedom deserves neither."

 

Even if cases like this...

 

http://www.youtube.com/watch?v=l7ZMlxNSx-Q&feature=related

 

are infrequent compared to gun accidents or murder... most people in the US seem to feel like the infrequent case where having a gun is a definite benefit should outweigh the dangers of living in a society where everyone else is equally legally unrestrained.

 

In other words... Yea guns!

[zapatos]

People fear loss of control.

 

If I have a gun I am in control. It doesn't matter if you have one or not because I have one and have some control over my situation. If no one is allowed guns, even though it may be likely that you do not have one when you show up, I know that I definitely do not have one and so I have limited control.

(Edit: Actually I am not necessarily referring to myself. I didn't buy a gun until I saw the mess in New Orleans after hurricaine Katrina.)

 

I remember a study not too long back (can't find it though) that found that many people who fear flying stated they would be less fearful if they could be in the cockpit. Didn't matter that they knew nothing of flying, they just felt that if they were up there then they would have some control.

Edited July 28, 2012 by zapatos