Public Information Post: About the AR15

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  • BrianY
    Left Wing Extremist
    • Apr 2004
    • 7942

    Public Information Post: About the AR15

    I thought it would be good to post this just so we all understand the weapon we're talking about. It's going to take a few posts...




    (excerpt)


    As it turns out, the original designer of the AR-15, working at a company called Armalite, had an earlier rifle called the AR-10, which it pitched to the military after the Korean War as a replacement for the M-1 rifle (the one they used in World War II). Armalite was using a screwy mix of metals at the back of the AR-10’s barrel (the part that is next to your face), and one of them blew up while the military was testing it, so the AR-10 lost a competition to what turned into the M14 (the wood-stocked rifle that honor guards march around with and twirl during drills). It’s worth noting that the AR-10 also fired the .308 Winchester bullets that the military was using (more on that later).
    Armalite redesigned the rifle to fire smaller .223 caliber bullets, stopped using screwy metals in the barrel, and called the result the AR-15. Unfortunately they already lost the contract and had a bad reputation to go with it (their last rifle blew up), so they sold the plans to Colt. Colt, in turn, pitched the AR-15 to the military, and after using the South Vietnamese Army as a guinea pig, then-Secretary of Defense McNamara bought a hundred thousand of them. The rest is a scene from Platoon.

    This means the AR-15 was definitely “designed to kill people as quickly as possible,” because it was designed for the infantry, and that is what the infantry does.

    Acrobatic Ammunition

    The next bit worth dealing with, which actually occurs earlier in Harris’ text, discusses the ammunition intended to be used by these types of rifles.
    These bullets also tend to tumble and fragment in the body, which makes them more lethal. However, one cannot say in every case that an assault rifle in the wrong hands is a greater threat to innocent life than a handgun. Rifle rounds travel at such high velocity that they sometimes pass through a person’s body before tumbling or fragmenting—doing less damage than one would expect from a handgun round. Conversely, these bullets are so light and frangible that they are sometimes stopped by barriers such as doors and wallboard.

    Before continuing, I think it’s worth talking a bit about the sizes of the ammunition that is being talked about. The .30-06 round (the big cartridge on the right in the sidebar image) was the ammunition used by the semi-automatic M-1 rifle, which is what the infantry carried in World War II. The .308 Winchester round (in the center), was used by the M-14 rifle, which replaced the M-1, and 5.56mm NATO round (on the left) is what’s used by the AR-15/M-16.
    I rather be an American than a Republican.
  • BrianY
    Left Wing Extremist
    • Apr 2004
    • 7942

    #2
    Re: Public Information Post: About the AR15

    continued from previous...

    One question when looking at this is “why did the military choose progressively smaller and smaller bullets?” Why did it trade in a .30-06 rifle for (effectively) a .22? There’s nearly 30 years of research behind that decision, which began (at least) with the Army looking at the effects of .22 caliber bullets when they hit people, in 1930. The Army followed that up after World War II with a lot of studies and reviews on how the infantry in World War II (and Korea) actually fought, how deadly rifles of different calibers could be, and yes, how the bullets behaved.

    To cover the history briefly, a review of battle reports from Europe showed that only 15-20% of infantrymen actually fired their rifles at enemy soldiers, but machine gunners tended to do so more often. That, combined with the results of other studies convinced the Army that they should issue every soldier a rifle with a switch which would turn it into a machine gun. Unfortunately for the Army, while an average soldier can carry a .30-06 rifle, a .30 caliber machine gun is another story altogether. So the Army started a competition, and ended up picking the M-14, which fired the shorter (but similarly sized) .308 Winchester round. They picked the M-14 because it could be fired like a machine gun more effectively than the M-1.

    In general, it can be stated that if the combined weight of rifle and ammunition is fixed at 15 lbs., a man carrying the Cal. .21 rifle would have an expectation of killing about 2-1/2 times as many targets as with the M-1 rifle.An Effectiveness Study of the Infantry Rifle, 1952

    While this was going on, the Army was also taking another look at the smaller .22 caliber rifles. This time, they were looking at how likely it was to kill someone at various ranges when using smaller caliber bullets. The math runs roughly like this: if a .22 is 25% less likely to kill someone as a .30-06, but you can carry twice as much ammo, then you can kill more people with a .22 than you can with a .30-06. The study complained they didn’t have enough ammunition to do a detailed study of the wounds that smaller bullets created, and it took another five years for someone to put this together with the report from 1930 and do the work.

    Eventually, however, the relevant experiments about wounding were conducted, and what they came up with were diagrams like those below.
    To start, the rifles and cartridges that the U.S. had been using (both the M-14 and the M-1) essentially ram right through their victims:

    What an M-14 bullet actually does to a person

    In the diagram above, the “Permanent Cavity” means the pieces of a person that are burned, compressed, or otherwise destroyed by the bullet. In other words, it means the bits that will have to grow back. The “Temporary Cavity” refers to the bits of a person that are mushed out of the way by the force of the bullet hitting, but not actually destroyed.
    I rather be an American than a Republican.

    Comment

    • BrianY
      Left Wing Extremist
      • Apr 2004
      • 7942

      #3
      Re: Public Information Post: About the AR15

      more...

      If we assume that an average American male’s chest size is still 40 inches around, and if we pull a number out of our asses and assume a very generous depth ratio of 0.71 (a man’s chest is 71% as deep as it is wide), the average American chest is going to be 11.6 inches deep, or about 29cm, which I’ve marked with the red line on the diagram. With those numbers, the bullet fired by an M-14 is, for lack of a better term, designed to blow out your back.
      Contrast that with damage from a full-metal jacket round that the AR-15/M-16 was designed to fire:
      …While a little bullet, being it has a low mass, it senses an instability situation faster and reacts much faster… this is what makes a little bullet pay off so much in wound ballistics.Eugene Stoner, designer of the AR-15, quoted in American Rifle: A Biography

      What an AR-15 bullet actually does to a person

      Again, the red line on the diagram indicates the back of an average American male’s chest. In this case, almost all the damage happens inside the person—you have a very small (less than 1/4 inch) hole that hides a bloody shredded bubble, several inches across, inside the victim’s body.

      On 9 June a Ranger Platoon from the 40th Infantry Regt. was given the mission of ambushing an estimated VC Company. [Five VC were killed:]
      Back wound, which caused the thoracic cavity to explode.
      1. Stomach wound, which caused the abdominal cavity to explode.
      2. Buttock wound, which destroyed all tissue of both buttocks.
      3. Chest wound from right to left; destroyed the thoracic cavity.
      4. Heel wound; the projectile entered the bottom of the right foot causing the leg to split from the foot to the hip.

      These deaths were inflicted by the AR-15 and all were instantaneous except the buttock wound. He lived approximately five minutes.

      ARPA report, cited in American Rifle: A Biography[IMG]file:///C:\Users\BRIAN~1.YAN\AppData\Local\Temp\msohtmlcli p1\01\clip_image007.gif[/IMG]
      So why is the smaller bullet so much more destructive? One of the things discovered during the 1930 study was what happens when you move the center of gravity towards the back of the bullet. The back of the bullet wants to keep moving after the front has slowed down. If this happens on a bullet that was already spinning, the back will try to cartwheel over the front.
      I rather be an American than a Republican.

      Comment

      • BrianY
        Left Wing Extremist
        • Apr 2004
        • 7942

        #4
        Re: Public Information Post: About the AR15

        last...

        Unfortunately for the victim, the front of the bullet doesn’t slow down quickly enough to cause tumbling until it’s already inside, so the bullet will try to cartwheel over itself inside their body. If the bullet is travelling fast enough when it hits, then the shearing force on the bullet trying to cartwheel through a person is stronger than the strength of the metal in the bullet, and the bullet will tear itself apart inside a person’s body.

        To get a better understanding of this, imagine the deep shock you feel when you belly-flop into a pool. Now imagine how bad it would be if you belly-flopped at Mach 3: you would splatter into little pieces when you hit.

        A thinner bullet means less metal, means less strength. So, by using thinner bullets and making them go faster, the bullet actually does a lot more damage than a bigger bullet. That’s also why the (shiny) casing around the 5.56mm round is nearly as big as the one on the much larger .308 Winchester—there’s more explosives packed into it, which makes the bullet travel faster when the gun goes off. Fast enough to make the bullet come apart if it hits something less than 300 feet away.
        You shouldn’t be surprised to learn that Army studies also found that when there was an infantry battle, the soldiers on either side were usually less than 300 feet away from each other.

        I think we can cut to the chase: the full-metal jacket ammunition designed for use with an AR-15 was intended to tumble and fragment inside anyone unfortunate to be shot with one, and the military would not have switched to the significantly smaller M-16 without knowing in advance that it was an all-around deadlier weapon than the rifles it was replacing. It’s supposed to hit a person standing less than 300 feet away at something like Mach 3, and splatter into little pieces.
        Does this mean full-metal jacket ammunition fired from AR-15 will always tumble and fragment? No, of course not. Nothing works as advertised all the time. But that is absolutely what it is supposed to do, and the fact that ammunition sometimes fails to be as vicious as it’s designers hoped doesn’t mean a damned thing.
        Strictly for comparison, here’s what a hollow-point bullet fired from a .357 Magnum does:

        What a .357 magnum bullet will do to a person

        Obviously, you’d rather be shot by none of these, but it’s worth noting that even a hollow-point from a .357 Magnum is tame compared to the round an AR-15 was designed to fire.
        I rather be an American than a Republican.

        Comment

        • Hugh Conway
          Banned
          • Jan 2012
          • 9162

          #5
          Re: Public Information Post: About the AR15

          You gun guys fetishize the weapon in your own fora and yet you think it's without meaning? That's some serious cognitive dissonance.

          Comment

          • BrianW
            not your average member
            • Nov 2002
            • 28191

            #6
            Re: Public Information Post: About the AR15

            Armalite was using a screwy mix of metals at the back of the AR-10’s barrel (the part that is next to your face),

            The part next to your face on an AR-10 or AR-15 is the stock. Any one who has been in the military probably remembers the "good cheek to stock weld" training mantra. Then forward of that is the receiver, and finally forward of that is the barrel.
            Last edited by BrianW; 08-02-2016, 01:00 PM.
            “Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime.”― Mark Twain,

            Comment

            • Hugh Conway
              Banned
              • Jan 2012
              • 9162

              #7
              Re: Public Information Post: About the AR15

              Oh - this is a talk at people thread. My bad.

              I'm sure there's no connection with the fetishizing of the AR-15 and the large number of AR-15 receiver Tap & die sets for sale on eBay at all.

              Comment

              • Canoez
                Did I say that out loud?
                • Sep 2007
                • 20615

                #8
                Re: Public Information Post: About the AR15

                IIRC, in the selection of the AR as a replacement for the M14 which is 7.62x51mm there were some considerations that included a lighter firearm, lighter ammunition, and the fact that the smaller 5.56x45mm was intended to wound the enemy as much as to kill them to cause more of the enemy to be engaged with tending or evacuating the wounded.
                "The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails."
                -William A. Ward

                Comment

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