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A 4 Pages Term Paper on Ballistics

     The science of bullets, or the events that occur inside and outside a gun when a bullet is fired from it is called Ballistics. There are three kinds of basic categories that ballistics is divided into and each focus on the events of that particular time frame only. Ballistics have taken the form of a research now a days and is no longer limited to be something only technical law enforcements agents and hunters should be aware of but also to ordinary people dealing with firearms in their everyday life for no matter what reason.

    Before we enter into the distinguishing phase of these categories, some of the terms that are usually heard but are meant with a different meaning when talking about ballistics. These include:

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Barrel Length: The size measured from the face of the muzzle to the base of the seated bullet or where the bullet is situated in the case neck.

Burning Rate: Burning rate is an arbitrary index of the quickness that burning propellant changes into gas. It is controlled by the chemical composition, the shape and size of the grains and the pressure at which the actual burning process takes place. Different powders have different burning rate depending on the grain.

Expansion Ratio: The ratio of the capacity of the powder chamber plus bore to the capacity of the powder chamber. All measurements are done by water as a medium of calculation, used as grains.

Loading Density: It is the ratio of the weight of the powder charge to the capacity the powder chamber. Generally, the more fully the powder charge fills the case the more consistent and accurate the load. On the other hand if the loading density is too low, it can cause erratic ignition, change in the pressure curve or even overly rapid burning of the powder charge.

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Pounds per square inch. (PSI):  This measurement is used to signify chamber pressure taken with an electric device The peak pressure recorded by a piezo-electric peak device usually reads about 5,000 PSI higher than the figure determined by the copper crusher method.

Powder Chamber Capacity: As with most interior ballistics capacity measurements it is usually expressed in grains of water. It is determined by measuring the weight of water that a fired case from the test firearm can contain with a bullet seated to its normal depth. Note that this varies with different bullets or seating depth as well as the dimensions of the chamber, and the brand of case.

Sectional Density: This is the ratio of the bullet's weight to its diameter

Charge Weight to Bullet Weight ratio: This is the ratio of the weight of the powder charge to the weight of the projectile

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Internal Ballistics

     Interior ballistics covers the events inside a gun that occur from the time the firing pin strikes the primer and everything that goes on until the bullet exits the muzzle. These include powder burning rates, chamber pressure, and muzzle velocity. From firing tests, sufficient data has emerged that when coupled with sound ballistic correlations have allowed the development of a mathematical model for the reasonable prediction of small arm internal ballistics.

    When we pull the trigger, the intense flame created by the priming compound fills the interior of the cartridge case and ignites the entire powder charge. The more the powder charge fills the case, the less the powder gases generated by the burning powder can expand without doing work and thus the more heat generated accelerates the burning process. In conclusion, a nearly full case of powder is more efficient then a partially filled one. The increasing pressures generated by the burning powder pushes the bullet down the barrel and if the bullet is tightly held into the neck of the cartridge, or if it is a tight fit in the rifling, then the confinement of the powder is accentuated and the burning proceeds more quickly than if these conditions were not present at all and we get higher pressures more quickly.

    If we have to keep barrel length reasonable, the way to get more velocity is to either change the burning characteristics of the powder so it gives higher pressures over a longer time, or to simply burn more powder by using a bigger cartridge case.

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External Ballistics

    An elongated bullet is inherently unstable, aerodynamically. When made stable gyroscopically by spinning, its center-of-gravity will follow the flight path. However, the nose of the bullet stays above the flight path just because the bullet has a finite length and generates some lift that causes the bullet to fly at a very small angle of attack with respect to the flight path. The angle of attack produces a small upward cross flow over the nose that results in a small lift force. This lift force normally would cause the nose to rise and the bullet to tumble as the nose rose more and more. That is where the spin comes in and causes the rising nose to precess about the bullet axis. When the spin is close to being right for the bullet's length, the precessing is minimized and the bullet velocity dies down and if it is too slow the bullet will not be as stable as it should.

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    Any other disturbing force such as a side wind gust could cause a difference in bullet nose precession but the effect would be quite small for a properly spin stabilized bullet. Most of the lift force is on the nose of the bullet and is proportional to the square of the bullet velocity as well as the nose shape and length. Long-nosed bullets for long-range match shooting can generate quite a bit more lift occurring farther ahead of the center- of-gravity and can produce a nasty pitch-up moment. That is why they require a faster than normal twist to stabilize them. Pistol or revolver bullets being relatively short and with little taper to the nose, require a slower spin for stability.

    The effect of the bullet’s tip shape and condition on the ballistic coefficient is an important factor to consider. Because modern bullets have soft points they are subject to damage and manufacturing tolerances that can alter the ballistic coefficient from bullet to bullet and across otherwise similar bullets.

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Terminal Ballistics

    Terminal ballistics is the science of what happens when the bullet strikes the target and the mechanism of incapacitation. It wasn't until accurate tissue simulants and modern high-speed x-ray photography started to be utilized that much of what happens began to be understood more fully. Even today there is still a lot of terminal ballistics being put forth by self-styled experts based on raw gathered data that is nothing but pet theories of the proponent, and some cases even manufacturer's incentives.

    There is an vital thing to note here, that is the depth of penetration. Law enforcement sometimes holds that too much penetration with ammunition used for self-defense is a bad thing. They warn that a bullet that passes through a target may hit someone else resulting in undesirable results. However, considering that it is estimated that 80 percent of the shots fired in law enforcement situations fail to even hit the target, the worry about the ammunition being penetrative enough is no longer of concern.

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    To give a practical example, we shall look at an instance where temporary cavity size may aid in the actual wounding and incapacitating process. That instance is when the bullet fragments during the creation of the temporary cavity. This can sometimes cause the tissue to suffer somewhat more damage than by just the bullets passage alone as the tissue can be cut or damaged during its stretched or stressed state by the bullet fragments and thus create a somewhat larger permanent cavity. If the wound is deep enough this can increase the incapacitation effect.

    However, modern medical science has shown us that the mechanism of incapacitation, while still not completely understood is based on two components; The permanent tissue and the nerve destruction caused by the cutting and crushing action of the bullet's passage. Rephrasing that, making the biggest diameter and deepest hole that you can. The other component is not as easily as quantifiable and is the physical and emotional state of the target. A target pumped up on adrenaline or affected by narcotic or psychotic drugs can be extremely resistant to bullet caused trauma while a target full of fear and self doubt may cease from a very minor wound. Since we are in no position to control the target's physical or mental state, we have to just worry about doing all damage that we can to the target.

    Gun ballistics has evolved over the last few years into a full-grown science detailing the actual events and cause reactions that govern those events. On the contradictory, it has also helped in promoting humanitarian issues by carefully laying out all possible damage details and detailed instructions to curious hunters who hunt for fun. The event discussed above, or the three categories of ballistics, are only the physically related aspects to a much larger issue that stands before us; to educate ourselves and our children more about the proper usage of firearms and the threats they pose at the same time as well as to monitor our environment carefully and to provide as much security to nature as it has provided us.

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