FIREARMS IDENTIFICATION AND INVESTIGATION INTRODUCTION
Ballistics (gr. ba'llein, "throw") is the science that deals with the motion, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and hurling projectiles so as to achieve a desired performance. A ballistic body is a body which is free to move, behave, and be modified in appearance, contour, or texture by ambient conditions, substances, or forces, as by the pressure of gases in a gun, by rifling in a barrel, by gravity, by temperature, or by air particles.
Firearm ballistics information is used in forensic science. Separately from ballistics information, firearm and tool mark examinations involve analyzing firearm, ammunition, and tool mark evidence in order to establish whether a certain firearm or tool was used in the commission of a crime.
Ballistics is sometimes subdivided into:
1. Internal ballistics, the study of the processes originally accelerating the projectile, for example the passage of a bullet through the barrel of a rifle;
2. Transition ballistics, the study of the projectile's behavior when it leaves the barrel and the pressure behind the projectile is equalized.
3. External ballistics, the study of the passage of the projectile through space or the air; and
4. Terminal ballistics, the study of the interaction of a projectile with its target, whether that be flesh (for a hunting bullet), steel (for an anti-tank round), or even furnace slag (for an industrial slag disruptor).
“Ballista” is a gigantic bow or catapult which was used to hurl large objects such as stones at a particular distance to deter animals or enemy forces.
Today, the word Ballistics is frequently used synonymously in the press and in the Police Parlance to Firearms Identification.
BALLISTICS
It is a science in itself because it evolved from systematic knowledge, research and development, training, experience and education of those who pioneered in this field.
Technically speaking, it refers to the "science of firearms identification which involves the scientific examination of ballistics exhibits such as: fired bullets; fired shells; firearms; and allied matters, used in crime.
Legally speaking, ballistics is the microscopic examination of fired cartridge cases and bullets together with the recording and presentation by means of photography of what is revealed by the microscope.
BALLISTICS THEORY
Ballistics is the scientific study of the propulsion and motion of projectiles such as bullets, artillery shells, rockets and guided missiles. Also includes the study of the destructive action of such projectiles.
The drag of a projectile moving head on is now usually divided into three parts: 1. bow resistance - due to air pressure at the head of the projectile;
2. skin friction - caused by the friction of air moving along the middle portion of the body; and 3. base drag - due to the under-pressure and disturbance of the air behind the base.
1. GALILEO, NEWTON, and LEIBNIZ established the principles of dynamics and the methods of calculus, studies which helped the rapid development of external ballistics.
2. GALILEO and NEWTON were both interested in the force called air resistance, now usually called aerodynamic drag, which reduces the speed of a projectile.
3. In 1707, CASSINI, an astronomer suggested measuring firearm’s muzzle velocity. INTERIOR BALLISTICS
It is the study of motion of projectiles within the gun barrel. The time during which the projectile is influenced by Interior Ballistics is very short. From the release of the firing pin to the moment the sound of the shot can be heard as it leaves the muzzle occupies only about 0.01 seconds, in a modern rifle.
Interior ballistics involves: 1. Ignition of the primer. 2. Flames is produced
3. Combustion of the gunpowder 4. Energy that is generated 5. Force/Pressure developed
6. Velocity of the bullet (from the chamber to the muzzle) 7. Rotation of the bullet
8. Engraving of the cylindrical surface of the bullet.
Interior ballistics deals with the temperature, volume, and pressure of the gases resulting from combustion of the propellant charge in the gun; it also deals with the work performed by the expansion of these gases on the gun, its carriage, and the projectile. Some of the critical elements involved in the study of interior ballistics are the relationship of the weight of charge to the weight of projectile; the length of bore; the optimum size, shape, and density of the propellant grains for different guns; and the related problems of maximum and minimum muzzle pressures.
Note the following:
The British engineer Benjamin Robins conducted many experiments in interior ballistics. His findings justly entitle him to be called the father of modern gunnery.
Late in the 18th century the Anglo-American physicist Benjamin Thompson made the first attempt to measure the pressure generated by gunpowder. The account of his experiments was the most important contribution to interior ballistics that had been made up to that time.
About 1760 French ballisticians determined the relationship of muzzle velocity to length of barrel by measuring the velocity of a musket ball and cutting off a portion of the barrel before taking the velocity of the next shot. By using the results of these experiments and advances in chemistry and thermodynamics, ballisticians developed formulas showing the relationship between muzzle velocity and weight and shape of projectile; weight, type, and grain size of powder charge; pressure and temperature in the barrel; and the size of the powder chamber and the length of the barrel.
Related Terms in Interior Ballistics
1. Action – term referring to the mechanism of a firearm.
2. Burning Rate - An arbitrary index of the quickness that burning propellant changes into gas. Burning rate is controlled by the chemical composition, the size and shape of the propellant grains, and the pressure at which the burning takes place. IMR 5010 powder is very slow burning and Bulls eye is fast burning.
4. Chamber Pressure – the pressure generated within the chamber erroneously called breeched pressure.
5. Charge Weight to Bullet Weight ratio - This is the ratio of the weight of the powder charge to the weight of the projectile.
6. Detonation – Chemical rearrangement of molecules into gas instead of solids to cause the high explosives to exert full power of shock. The speed of detonation varies in different explosive but in some it is as high as 7000 yards in a second.
7. Energy - is measured in foot-pounds, and one foot-pound means that amount of energy, which would be capable of lifting a weight of one pound through a distance of one foot Drop-Block Action- That type of action in which the breechblock rises and forces vertically in cuts in the receiver side walls. Lever actuated as a rule.
8. Expansion Ratio - The ratio of the capacity of the powder chamber plus bore (in grains of water) to the capacity of the powder chamber (in grains of water).
9. Foot – Pound - the amount of work required to raise one pound one foot high against the force of gravity. 10. Foot second - velocity expressed in foot per second.
11. Gas - a fluid resulting from the combustion of gun powder with a relatively great expansion and spontaneous tendency.
12. Hangfire - Occurs when a cartridge fails to explode on time or delayed in firing.
13. Knocking Power - the power of the bullet which delivers a very heavy paralyzing blow that put the victim down and may then recover if the wound inflicted upon is not fatal.
14. Loading Density - The ratio of the weight of the powder charge to the capacity of the powder chamber (case). It is usually expressed as the ratio of the charge weight to the capacity the powder chamber in grains of water. (See below.) Generally, the more fully the powder charge fills the case the more consistent and accurate the load will be. On the other hand if the loading density is too low, (too much free space in the case) it can cause erratic ignition, change in the pressure curve (moving the peak towards the muzzle), or even overly rapid burning ("detonation") of the powder charge. (One reason manuals list minimum or starting loads.)
15. Misfire – total failure of a cartridge to discharge. This is different from hang fire which merely a delayed combustion, while misfire a complete failure eve to start combustion.
16. 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.
17. Pressure – Outward push of gases from powder combustion against cartridge case, chamber and bore. 18. Sectional Density - The ratio of the bullet's weight (in pounds) to its diameter.
19. PSI - Pounds per square inch. It is often seen designated as PSIA. This designation is now used to signify a measurement of chamber pressure taken with a piezo-electric device. Piezo-electric units operate in a similar fashion to the copper crusher units but use a reusable crystal "crusher" that changes its electrical properties in response to pressure. When connected to suitable recording equipment the entire pressure pulse history can be recorded or displayed. 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.
20. Recoil – the equal and opposite reaction of the gun against the forward movement of the bullet during the explosions.
21. Residual Pressure – the pressure remaining in the chamber after the bullet has left the barrel. EXTERIOR BALLISTICS
Exterior Ballistics deals with the motion of projectiles from the time they leave the muzzle of the firearm to the time they hit the target. The flight of most bullet or projectile does not exceed 30 seconds at maximum range, which for almost any firearms is obtained at an elevation of about 33.
CONDITIONS - refers to the natural laws.
a. velocity - speed per unit of time ex. M16 - 3,300 ft/sec. b. energy - fatal equivalent of a bullet.
c. yaw - the unstable rotating motion of a bullet.
d. gyroscopic action - refers to the stillness of its rotating motion and attained its highest momentum or stability in flight and penetrating power.
In exterior ballistics, elements such as shape, caliber, weight, initial velocities, rotation, air resistance, and gravity help determine the path of a projectile from the time it leaves the gun until it reaches the target.
Until the middle of the 16th century it was believed that bullets move in straight lines from the gun to the target and that shells fired from mortars describe a path made up of two straight lines joined by an arc of a circle. The Italian mathematician Niccolò Tartaglia, in a published work on gunnery, claimed that no part of the path of a projectile could be a straight line and that the greater the velocity of the projectile the flatter its path. Tartaglia invented the gunner's quadrant used to determine elevation of the muzzle of a gun. He is and Italian scientist who a book in which he said that the trajectory of a bullet was really a continuous curve. He directed some firing tests to determine this angle, and discovered that it was near 45 degrees and he noted that the trajectory was continuously curve.
Galileo proved that in a vacuum a projectile describes a parabolic arc. The description of the law of gravitation by the British scientist Sir Isaac Newton made plain the cause of the curvilinear motion of projectiles. By the use of calculus he determined the momentum transferred from the projectile to the particles of air at rest; this method of calculating air drag has been superseded by the use of tables prepared from experimental firings.
Two methods have been used to determine the velocity of a projectile after it leaves the gun. One method measures the momentum of the projectile; the other measures the time required for the projectile to travel a given distance. The first method is the older, and in the past, when guns and projectiles were small, velocities low, and ranges short, the results were sufficiently accurate for most practical purposes. The ballistic pendulum and gun pendulum were used to measure projectile momentum, but these devices have been supplanted by cheaper and more accurate machines working on the principles of the second method.
The ballistic pendulum was developed about 1743 by Robins, who was the first to undertake a systematic series of experiments to determine the velocity of projectiles. The principle of the ballistic pendulum, as well as of the gun pendulum, which was developed by Thompson, is the transfer of momentum from a projectile with a small mass and a high velocity to a large mass with a resultant low velocity.
The ballistic pendulum consisted of a massive plate of iron to which was bolted a block of wood to receive the impact of the projectile; the pendulum was suspended freely from a horizontal axis. The block, when struck by the projectile, recoiled through a certain arc that was easily measured. Knowing the arc of recoil and the masses of the projectile and the pendulum, the velocity of the projectile could be determined by calculation. The ballistic pendulum was able to withstand the impact of musket balls only; however, by determining the relations that should exist between the caliber, length of barrel, and charge of power, Robins substantially advanced the science of gunnery.
By the second method, the velocity of a projectile is determined by measuring the time required for it to travel a known length of its path. Numerous machines have been devised for this purpose; in 1840 the British physicist Sir Charles Wheatstone suggested the use of electricity for measuring small intervals of time. This suggestion led to the development of the chronograph, a device for recording, by electrical means, the time required for a projectile to pass between two screens of fine wire.
The formulas and tables for the exterior ballistics of each new type of gun or cannon are more or less empirical and must be tested by actual experiment before the aiming devices can be accurately calibrated.
Further, exterior (external) ballistics refers to the attributes and movements of the bullet after it has left the gun muzzle. It includes:
1. Muzzle blast - the noise created at the muzzle point of the gun due to the sudden escape of the expanding gas coming in contact with the air in the surrounding atmosphere at the muzzle point.
2. Muzzle energy - energy generated at the muzzle point.
3. Trajectory - the actual curved path of the bullet during its flight from the gun muzzle to the target. The following are the kinds of trajectory: straight horizontal line - parabola-like flight - vertical drop
4. Range - the straight distance between the muzzle point and the target.
a. Accurate (effective) range - the distance within the shooter has control of his shots, meaning he can place his shots at the desired spots.
b. Maximum range - the farthest distance that a projectile can be propelled from a firearm.
* While the range at which the ordinary pistol and revolver are supposed to be effective in only 50-70 yards, all of them can send their bullets much further than that and are capable of inflicting fatal wounds at distances up to one mile, depending on the caliber and gunpowder content.
5. Velocity - rate of speed of the bullet per unit of time.
Long barrel rifle – up to 3,000 yards accurate range and its hinge muzzle velocity of 1000-4000 ft./sec.
* Bullets from rifled weapons spin at 2000-3000 revolutions per second, but over the first few yards of trajectory – distance varies with the weapon – their flight is slightly unstable; the end of the projectile wobbles before it picks up a smooth flight path. This phenomenon is called “TAILWAG”, and is of considerable important in evaluating gunshot wounds. A bullet with “tailwag” does not strike its target clearly.
6. Air resistance - resistance encountered by the bullet while in flight. 7. Pull of gravity - downward reaction of the bullet while in flight. 8. Penetration - depth of entry on target.
Note on the following Contributors:
1. 1707 - Cassini. Suggested measuring of firearms muzzle velocity
2. 1857 – Monsieur Noiles. Published a thesis titled ‘Les Plaies Feu Courtes’. His thesis dealt with the subject of wounds made by small firearms.
3. 1748 - Henry Shrapnel. He invented the shrapnel, which disperse its load of case shot with a small bursting charge, increasing the effective range of case.
4. 1898 – Mr. Corin in Paris, France. Published an article titled “La Determination de La Distance a’Laguelle un Coup de Feu a e’te’ Tire” (Determination of the distance at which a shot has been discharged from a firearm).
5. 1900 – Dr. Albert Llewellyn Hal in Buffalo, New York (USA). A very significant article entitled “The Missile and the Weapon” was published in the June issue of the Buffalo Medical Journal.
6. 1903 – Mr. E.J. Churchill in London, England (uncle of Robert Churchill of later fame as a firearms examiner for the United Kingdom). He provided testimony as to some experimentation that he had performed involving the distance of which a shot had been fired into a human skull.
7. 1900 - Dr. Albert Llewellyn. He wrote an article entitled “The Missile and the Weapon”, which dealt with a variety of issues to include how measurement of land and groove markings are made on bullets. He also discussed the examination of gunpowder residues in barrels of firearms and the changes that take place over time after the weapon is fired.
8. 1921 - Mr. Jorge T. Filho. He published an article entitled “Estimation of Distance from which a Bullet was Fired” (“Da Diagnose da Distance nos Tiros de Projecteis Multiplos Chumbo de Caca”).
9. Emile Monnin Chamot. He authored a 61-paged monograph entitled “The Microscopy of Small Arms Primers”.
Note on the following Terms in Exterior Ballistics:
1. Accuracy Range – The maximum distance at which a particular gun and cartridges will consistently place all shots in the standard target for that distance.
3. Back Curve - This is that portion of the bullets trajectory that drops below the critical zone beyond the point blank range. Past this point the trajectory begins to drop off very rapidly with range and the point of impact becomes very difficult to estimate.
4. Ballistic Coefficient – The means that the bullet may lose its speed very rapidly during its flight the air. This is a number that relates to the effect of air drag on the bullet's flight and which can be used to later predict a bullet's trajectory under different circumstances through what are called "drag tables."
5. Bullet Energy – the power possessed by a moving bullet, or in other words, its ability to keep going when it meets an obstacle and to do work on the obstacle is immense importance, for obviously the more power a bullet has an the harder it is to stop the more effective it can be as a weapon
6. Bullet Trajectory - This is the bullet's path as it travels down range. It is parabolic in shape and because the line of the bore is below the line of sight at the muzzle and angled upward, the bullet's path crosses the line of sight at two locations.
7. Critical Zone - This is the area of the bullet's path where it neither rises nor falls greater than the dimension specified. Most shooters set this as ± 3" to 4" from the line of sight, although other dimensions are sometimes used. The measurement is usually based on one-half of the vital zone of the usual target. Typical vital zones diameters are often given as: 3" to 4" for small game, and 6" to 8" for big game and anti-personnel use.
8. Drift - is the curve taken by the bullet while in flight. A right hand rifling curves to the right while that of the left and rifling curves to the left.
9. Effective Range- The maximum distance at which a bullet may reasonably be expected to travel accurately and kill a particular type of live targe
10. Extreme Range – The greatest distance the bullet will travel when the cartridge is fired.
11. Flat Trajectory - A comparative term used to indicate very little curvature in the flight in the bullet from muzzle to point of impact. When the velocity is high, comparatively flat trajectory.
12. Gallery Range - The indoor target range. National rifle association of America, gallery rules required stance from firing point to target of 50 feet or 75 feet for.22 rim fire riffle; 50 feet or 60 feet for .22rim-fire pistols. On properly constructed indoor ranges, firing may be conducted with center fire pistol and revolvers at ranges of 25 yards and 50 yards. Such installation are generally referred to as “indoor range” the term “gallery” being applied usually only to the short range . 22 caliber installation.
13. Gallery Range - The indoor target range. National rifle association of America, gallery rules required stance from firing point to target of 50 feet or 75 feet for.22 rim fire riffle; 50 feet or 60 feet for .22rim-fire pistols. On properly constructed indoor ranges, firing may be conducted with center fire pistol and revolvers at ranges of 25 yards and 50 yards. Such installation are generally referred to as “indoor range” the term “gallery” being applied usually only to the short range . 22 caliber installation.
14. Initial Point - The range at which the bullet's trajectory first crosses the line of sight. This is normally occurs at a range of about 25 yards.
15. Instrument Velocity - the velocity of a projectile measured by the scientific instrument called chronograph, at a specified point on its trajectory. Always lower than the muzzle velocity.
16. Key-hole Shot – the tumbling of the bullet in its flight and hitting the target sideways as a result of not spinning on its axis.
17. Maximum Point Blank Range - This is the farthest distance at which the bullet's path stays within the critical zone. In other words the maximum range at which you don't have to adjust your point of aim to hit the target's vital zone. Unless there is some over riding reason to the contrary shots should not generally be attempted much past this distance. In the words of the Guru, "It is unethical to attempt to take game beyond 300 meters." If you do, you should write yourself a letter explaining why it was necessary to do so. An approximate rule of thumb says that the maximum point blank range is approximately your zero range plus 40 yards.
18. Maximum Range – the farthest distance that a projectile can be propelled from a firearm.
19. Maximum Ordinate - This is the maximum height of the projectile's path above the line of sight for a given point of impact and occurs somewhat past the halfway point to the zero range and it is determined by your zeroing range.
20. Mid-range Trajectory - This is the height of the bullets path above the line of sight at half way to the zero range. It does not occur at the same range as the maximum ordinate height which can be greater.
21. Minute of Angle (MOA) - A "minute" of angle is 1/60 of a degree which for all practical purposes equates to 1 inch per 100 yards of range. Thus 1 MOA at 100 yards is 1 inch and at 300 yards it is 3 inches. The term is commonly used to express the accuracy potential of a firearm.
22. Point Blank Range – Popularly used to indicate the distance the bullet will travel before it drops enough to require sight adjustment. A short fired so closed to the target that no sighting is necessary for effective aiming.
23. Ricochet – The bouncing off or deflection of a bullet from its original trajectory (normal path) after striking a resistant surface.
24. Shocking Power – the power of the bullet that results in the instantaneous death of the victim.
25. Stopping Power – the power of the bullet that put the victim out of action instantly. So it should be understood that stopping power is not necessarily the same thing as killing power. However, stopping power depends very largely on the location of the sot.
26. Target – an object at which the firearm is aimed and discharged.
27. True Drop – the actual distance the bullet falls during the time of flight to the target. This is not the same as what we speak of when we discuss drop in the ordinary sense, which is more properly termed effective or apparent drop 28. Zero Range - This is the farthest distance at which the line of sight and the bullet's path intersect.
TERMINAL BALLISTICS
It is the study dealing with the effect of the impact of the bullet on the target. Penetration of the bullet is of prime interest. Penetration is important also in determining safety requirements for target backstops. They are important to both sportsman and military.
TERMINAL BALLISTICS involves:
1. Terminal accuracy - size of the bullet grouping on the target.
2. Terminal energy - energy of the projectile when it strikes the target. Also known as striking energy. 3. Terminal penetration - depth of entry of the bullet in the target.
4. Terminal velocity - speed of the bullet upon striking the target.
Terminal ballistics also deals with the destructive actions and effects that occur at the end of the projectile's flight as an integral and un-deformed body. The flight may end in one of two ways:
1. the projectile may strike a solid obstruction, or
2. its metal case may be broken by the explosion of a bursting charge SHOTS BALLISTICS - deals with the attributes and properties of shots and pellets.
CHOKE - When the diameter of a barrel of a shotgun is the same throughout the bore, it is called true cylinder.
The bore of the gun is sometimes constricted near the muzzle end. That is, the diameter near the muzzle end is slightly smaller than the diameter of the bore of the rest of the barrel. The barrel is said to be choked.
Full – if reduced by one mm; half if reduced by one-half mm; quarter if reduced by ¼ mm; and improved cylinder if reduced by about 1/10 mm.
The amount of spread in the shot is controlled by the choke. If a barrel will put 70 percent of its shot charge in a 30-inch (76-centimeter) circle at 40 yards (37 meters), it is called full choke. Modified choke will deliver about 60 percent; improved cylinder about 50 percent. A full choke 12-gauge gun will kill ducks that are about 60 to 65 yards (55 to 59 meters) away. Chilled Shot – shotgun pellets made from lead especially hardened by the addition of a slight amt. of antimony. WOUND BALLISTICS – It is the study of the effects of projectile to human body.
Gunshot Wound (GSW). It is an open wound produced by the penetration of bullet slug within the tissues of the body. The bullet which was propelled from the gun as well as the flame from the heated expanded gases in short range fire is the one that produces injury.
Three Basic Kinds of GSW Distinguished by the Proximity of the Weapon
1. Contact – gun muzzle pressed against, or within an inch or two, of the body. 2. Close discharge – 6 inches to 2 ft.
3. Distance Discharge – over 2 ft. or 3 ft.
Range of Fire - an important aspect of forensic ballistics.
1. Muzzle Pattern – indicates contact wound and are often observed in suicide cases. The whole charge (projectile, wads, if any, smoke, unburnt or semi-burnt powder particles and hot gases) enter into the target. No burning, blackening and tattooing are observed. Instead, they are observed inside the hole through careful examination. The edges are found ragged (torn in star shape) and the wound is like an exit wound.
2. Scorching – caused by the flame or hot gases not by the hot projectiles as is commonly believed. It is also known as burning or charring.
3. Blackening – caused by the deposition of smoke particles by all types of powders at close ranges. Being light particles, they soon lose their velocity and get deposited on any material available in the path.
4. Tattooing (a.k.a. peppering) – caused by the embedding of unburnt and semi-burnt powder particles into the surface of the target. These particles are slightly heavier than the smoke particles. They retain motion to somewhat longer intervals and consequently cause tattooing to a distance of about one and a-half times blackening range. Other GSW Characteristics
1. Pink Coloration – caused by absorbed carbon monoxide in the skin and flesh.
2. Dirt Ring – deposited by some projectile (which carry greases on them) around the wound. Existence of this indicates the entrance side of a firearm injury & does not indicate range.
3. Contusion – caused by the impact of the projectile (reddish dark to bluish black - varies somewhat with the age of the injury). It takes the form of a belt around the wound. It is of uniform in thickness.
4. Foreign Materials – Their presence not only permits the identification of the firearms injury but they also permit a fairly reliable guess of firearm.
Factors influencing entrance and exit gunshot wounds
1. Kind of weapon - The higher power the weapon is the more destructive to the tissues of the body.
2. Caliber of the weapon - The higher the caliber of the wounding bullet, the greater will be the size of the wound of entrance, hence, greater destruction to the tissues.
3. Shape and composition of the missile - The conical shape free end of the bullet slug has more penetrating power but less tissue destruction, while bullet slug with hemispherical free end had less penetrating but more destruction to the tissues.
* Some bullets were made to be deformed upon heating the target like the hallow point, dum-dum and soft point bullet. Bullets made of hard metals like the magnum 44 and the armor-piercing bullet are not usually
deformed upon hitting the target. Other bullets and the fragments may cause further injury to the body. The tracer bullet is in flame during its flight to the air and may caused burn upon hitting the body and this bullet is also used in targeting the low flying airplane.
4. Range of fire - the injury is not only due to the missile but also due to the pressure of the heated expanded gases, flame and articles of gunpowder. However, in long range fire, the characteristic effect of the bullet alone will produce the injury.
5. Direction of fire - A right angle approach of the bullet to the body will produce a round shape wound of entrance in short distance fire, while in acute angle of approach the bullet will produce an oval shape wound of entrance with contusion collar widest on the side of the acute angle of approach and a tendency for the bullet to deflect to another direction upon hitting the target.
6. Part of the body involved - When the bullet hit the soft tissues of the body; the bullet penetrates and usually without any change in direction, however upon hitting the bones and other hard body structures the bullet may fracture the bones causing further injury or may deflect to another direction.
Description of the wound of entrance is based on the distance of the body from the fired gun
1. Contact fire. This is burst due to the explosion of the powder which produces the heated and expanded gases. There is burning of the tissues because it is within the flame zone; singeing of the hair; and particles of gunpowder in and around the wound of entrance; skin is separated from the underlying tissues in the affected area and the blasted tissues are cherry red in color because of the presence of carbon monoxide; pressure of the bullet will caused caving-in or excavation of tissues and the contusion collar is seen around the wound of entrance. The size of the wound is rather small.
2. Near contact up to six inches distance. There is bursting of tissues, burning and blackening of the skin as in contact fire but the particles of gunpowder are present inside as well as around the wound of entrance. The shape of the wound maybe lacerated or slit-like and the size is larger than the diameter of the missile. The excavation of tissues due to the pressure of the penetrating bullet slug but it can be severe as in contact fire.
3. Distance above six inches up to 24 inches. The size of the wound gradually approximates the size of the missile. The farther the target, the lesser the burning or blackening of tissues, gun powder tattooing, singeing of the hair and excavation of tissues and lesser until they disappear beyond the 24 inches distance.
Differentiation between gunshot wound of Entrance and Wound of Exit Differential points
1. Size of the wound 2. Edge of the wound 3. Shape of the wound 4. Contusion collar 5. Gunpowder tattooing 6. Presence or absence 7. Protrusion of tissue 8. Paraffin test Wound of Entrance smaller than the missile Inverted
Round or oval present in contact and near contact fire always present
Absent
+ in contact and near fire
Wound of Exit
bigger than the missile Everted
no definite shape
absent
absent
maybe absent if the slug is lodged inside the body
maybe present
negative
Determination whether the gunshot injury is Suicidal, Homicidal or Accidental A. Evidence to prove that gunshot wound is suicidal
1. Accessibility of the involved part to the hand of the victim 2. Usually only one gunshot wound
3. Usually the distance is short range or class range 4. Presence of suicide note
5. History of frustration or despondency of the victim 6. Presence of cadaveric spasm on the hand of the victim
7. Exclusion of other evidences to prove that it is not suicide B. Evidence that the gunshot wound is homicidal
1. Wound is located at any part of the body
2. Victim usually at a certain distance from the assailant
3. Signs of struggle (Defense wound) maybe present in the victim 4. Disturbances of the surroundings.
5. Wounding weapon usually not found at the scene of the crime 6. Testimony from the witnesses
C. Evidence that gunshot wound is accidental 1. Usually only one gunshot wound 2. Wound located at any part of the body
3. Absence of personal grudge between the victim and the one who fired the gun 4. Testimony from witnesses
Take note:
Shotgun Wound - It is an open wound produced by the penetration of pellets or shots within the tissues of the body. In shotgun fire, the pellets penetrate and usually lodged inside the body and a tendency for a wider dispersion of pellets at a certain distance except in contact and near contact fires.
Characteristics of the Shotgun Wound of Entrance
1. Contact fire - irregular with bursting of the affected tissues due to explosion of the heated and expanded with accompanying flame causing burning of the skin and the tissues. There is singeing of the hair; presence of wads and particles of gunpowder inside the wound of entrance.
2. Near shot up to six inches distance. There is marked laceration of the skin and destruction of tissues due to the pressure of explosion. The burning on the surface of the skin and particles of gunpowder are present inside and around the wound of entrance. There is singeing of the hair as well as pieces of wads inside and outside the wound of entrance.
3. Distance about one yard. The pellets penetrate the tissues as one mass making the wound with irregular edge of the wound of entrance. There will also be blackening of tissues with slight burning, singeing of the hair or gunpowder tattooing.
4. Distance about two to three yards. The wound of entrance has a big central hole with ragged edges and a few stray wounds of entrance around the central hole. At this distance, there will be no more blackening or burn ing of the skin, gunpowder tattooing, singeing of the hair and pieces of wads or near the wound of entrance.
5. Distance of four yards. A small group of pellets may penetrate the tissues producing a central core, although plenty of pellets in a wider dispersion may produced separate wound of entrance. The pellets dispersed about one and a half the distance in yards in non-choked barrel while in full-choked bore the dispersion is one half less but there is a wider dispersion in short barrel shotgun.
Points to consider in the reporting of gunshot and shotgun injuries 1. Detailed description of the gunshot and shotgun wound 2. Location of wound in the body
3. Measurement of the wound as to diameter and depth 4. Number of wound of entrance and exit
5. Direction and length of the bullet tract 6. Organs or tissues involved
8. Diagram, photograph, sketch or drawing of the gunshot or shotgun wound Effects or complications of wound
1. Hemorrhage – Bleeding. It is the loss of blood from the ruptured vessel secondary to trauma or existing pathology. 2. Direct mechanical injury - This is the direct damage to the tissues
3. Shock - It is disturbance of the balance of fluid in the body characterized by fall in blood pressure, decreases blood flow or blood volume in the body.
4. Infection. It is the appearance, growth and multiplication of the micro-organism in the living tissues.
5. Embolism. It is the clogging of the blood vessel by foreign bodies such as air or bits of fats or septic embolus causing blocking to the blood flow to the distal tissues supplied by the blood.
Points to consider in the reporting of wound: 1. Character of the wound
2. Location of wound in the body
3. Measurement of the wound - It is declared in inches, centimeters and millimeters. a. Length b. Width c. Depth 4. Number of wound 5. Direction of wound 6. Organs involved 7. Severity of the wound
8. Period of healing or incapacity of the victim. Other pieces of evidence in dealing with the wound
1. Evidence from the wounding weapon
a. Presence of blood stains, bits of tissues and other body fluids on the wounding weapon. 2. Evidence from the victim as well as the assailant
a. Presence of blood stains, bits of tissues and other body fluids on the victim or assailant b. Presence of wound on the victim as well as the assailant
c. Effects or complications of wound such as found in the clinical manifestations on the victim 3. Evidence from the scene of the crime
a. Presence of blood stains or drops of blood on the streets or flouring, walls, furniture and other materials at the scene of the crime
b. Presence of bits of tissues, torn clothing and other body fluids at the scene of the crime Take Note:
SIR SYDNEY SMITH – founder of the Medico-Legal Faculty at Cairo University and later Regis Professor of Forensic Medicine at Edinburgh, was one of the leading exponents in studying entrance and exit wounds, powder burns and powder “tattooing” on human skin and other medical phenomena associated with gun fire.
Studies involving Terminal and Wound Ballistics
1857 – Monsieur Noiles. He published a thesis titled ‘Les Plaies Feu Courtes’. His thesis dealt with the subject of wounds made by small firearms.
1889 – Mr. A. Lacassogne of Lyon, France. He published a paper tided “La Deformation Des Balles de Revolver” (Deformation of Revolver Bullets) in Volume 5. Archives de l’Antropologie Criminelle et Des Sciences Penales.
1748 - Henry Shrapnel. He invented the shrapnel, which disperse its load of case shot whit a small bursting charge, increasing the effective range of case.
Anomynous author. Published a thesis an article entitled “Entrance Wounds and Powder Markings”.
Mr. Louis B. Wilson. He published an article entitle “Dispersion of Bullet Energy in Relation to Wound Effects”.
P. Chavigny and E. Gelma. They authored an article entitled “Fissures of the Skull by Revolver Bullets at short-range”.
J. Howard Mathews. Chairman of the Department of Chemistry at the University of Wisconsin. In this first criminal case, he was involved on the metallographic analysis of bomb parts used to kill an individual. FORENSIC BALLISTICS
It is the study of Firearm Investigation and Identification of firearms by means of ammunition fired through them. This is the real branch of the science which the police use as their guide in field investigations. This includes the following:
1. Field Investigations - conducted by the first officers on the case in the field when they investigate a case or cases wherein firearms have been used. This is a routine job of the investigating officers, and this involves recognition, collection, marking, preservation, and transmittal of ballistics exhibits like fired bullets, fired shells, firearms and allied matters.
2. Technical examinations of the ballistics exhibits - This is the job performed by the firearms examiners in the laboratory. It involves marking of the evidence firearms, test firings of evidence firearms to obtain test bullets and test shells for comparative purposes, photomicrography under the bullet comparison microscope, preparation of comparative charts, and the making of reports on the findings and observations of the firearms examiners. 3. Legal proceedings - Court Trials - wherein the ballistics report of the firearm examiner and the ballistics exhibits
are presented during the trial of the case in a court of justice. Take Note:
FORENSIC - As applied to ballistics, or to any other subject, suggest a relationship to Courts of Justice and legal proceedings.
FORUM – It is a Latin word from which forensic was derived, meaning a marketplace, where people gather for "public disputation" or "public discussion". Thus, the title "Forensic Ballistics" aptly describes the subject under consideration - the science of investigation and identification of firearms and ammunitions used in crimes. The terms "Ballistics", Forensic Ballistics" and "Firearms Identification", have come to mean one and the same thing in the minds of the public, and they can be used interchangeably.
Studies concerning Forensic Ballistics
1835 - Henry Goddard. In one of his case in England, where a homemaker was shot and killed, he was able to identify the mold mark – the mold is used to manufacture lead balls from molten leads – on the field projectile. He was the bullet, which could be traced back to the mold. He also examined the paper patch – the paper patch provides the seal between the ball gunpowder firearms – was able to identify it as having been torn from a newspaper that was found on the room of the guilty servant.
Paul Jesrich. He took photomicrographs of two bullets to compare, and subsequently individualize them through the minute differences.
1905 - Mr. Kockel. He published an article entitled “The Expert Examination of Fired Bullets”.
1912 - Professor V. Baltahazard. He devised a series of procedures to identify fired bullets to the firearms from which they were fired. He studied the firearms by taking an elaborate series of photographs of test fired bullet from the firearms as well as evidence bullet. He also applied these same specilalized photographic techniques to the examination and identification of cartridge casings using firing pin, breech face, ejection and extractor marks.
1913 - Professor Balthazard. Published the first article individualizing bullet markings.
1922 - Mr. C. Williams. He wrote an article entitle “Fingerprints on Bullets” which appeared in Outdoor Life magazine. 1920 - R.E. Herrick. He published an article entitled “Ballistics Jurisprudence”.
November 1924 – Dr Sydney Smith. He wrote an article concerning the details of the investigating that appeared in the British Medical Journal in January 1926. He relates that he believes that scientific examination of firearms and projectiles in Great Britain had its beginning as a result of the publication of his report on the case.
1920 - COL CALVIN H. GODDARD (M.D., U.S. ARMY) pioneered the introduction of this science in Criminology courses in the different universities.
1947 - Col Goddard came to the Philippines when Gen. Castaneda was ambushed together with his aid, Col Salgado in Kamias, Quezon City, both died.
1924 – Captain Edward C. ‘Ned’ Crossman. A well-known shooter and sports writer, examined firearms evidence for the Los Angeles County Sheriff in April 1925, in New York City, New York (USA), THE Bureau of Forensic Ballistics was established by C.E. Waite, Major (later Colonel) Calvin H. Goddard, Philip O. Gravelle and John H. Fisher.
1934 - Major Sir Gerald Burrard. He wrote a book entitled “The Identification of Firearms and Forensic Ballistics”, which discussed many early cases that occurred throughout the British Empire.
1935 Major Julian S. Hatcher. He wrote and published; “Textbook of Firearms Investigation, Identification and Evidence” together with the “Textbook of Pistols and Revolvers.”
1944 – John E. Davis. He joined the Police Department in Oakland, California establishing its first criminology laboratory.
Derechter and Mage. They wrote an article entitled “Communication on the Identification of Fired Bullets and Shells”. Arthur Lucas. He published an article entitled “The Examination of Firearms and Projectiles in Forensic Cases”. Jack D. Gunther & Professor Charles O. Gunther. They published the entitled “The Identification of Firearms”,
which provided additional information about the principles of firearms identification with approximately one-half of the book discussing in great detail the Sacco-Vanzetti case to include reprinting large portions of the actual court transcript. They also discussed the need for the science of firearm identification to utilize the scientific methodology.
1958 – John E. Davis. An eminent criminals and Director of the Oakland Police Department (CA) Criminalistics Section (Crime Lab) wrote a book titled “An Introduction to Tool Marks, Firearms and the Striagraph”. In his book, Davis provided excellent information about the examination and identification of firearms and tool mark evidence.
1996 – Tom A. Warlow. He published a text on firearms identification titled “Firearms, the Law and Forensic Ballistics”. Warlow has written a useful text that contains excellent information for firearm and toolmark examiners. 1997 – Brian J. Heard. He published a text on firearms identification titled “Handbook of Firearms and Ballistics
Examining and Interpreting Forensic Evidence”. SUBJECTS OF BALLISTICS STUDY
FIREARMS
A firearm is a weapon that fires either single or multiple projectiles propelled at high velocity by the gases produced through rapid, confined burning of a propellant. This process of rapid burning is technically known as deflagration. In older firearms, this propellant was typically black powder, but modern firearms use smokeless powder or other propellants.
The term gun is often used as a synonym for firearm, but in specialist use has a restricted sense—referring only to an artillery piece with a relatively high muzzle velocity and a relatively flat trajectory, such as a field gun, a tank gun, an anti-tank gun, or a gun used in the delivery of naval gunfire.
Firearms are sometimes referred to as small arms. Small arms are weapons which can be carried by a single individual, with a barrel bore of up to approximately 0.50 inch (12.7 mm). Small arms are aimed visually at their targets by hand using optical sights. The range of accuracy for small arms is generally limited to about one mile (1600 m), usually considerably less, although the current record for a successful Sniper attack is slightly more than 1 1/2 miles.
Firearm (Technical) is an instrument that is used for the propulsion of projectile by means of the expansive force of gases of burning gunpowder.
Firearms or Arm (legal – Sec. 877 of the RAC and Sec. 290 of NIRC) – includes rifles, muskets, carbines, shotguns, pistols, revolvers and all other weapons from which a bullet, a ball, a shot, a shell or missiles may be discharged by means of
gunpowder or other explosives. The term also includes air rifles, except that are in small in caliber and usually used as toys. The barrel of any firearm is considered a complete firearm for purposes of Section 877 of the Revised Administrative Code.
Take Note:
Rifle – long rifle bored firearm designed to hit targets at a greater or longer distance, with spiral grooves to fire only a single shot.
Musket – long smooth bored firearm that is designed to prepare a single shot.
Shotgun – long smooth bored firearm having a barrel of 25-30 inches long and designed to shot birds in flight; long smooth bored firearm and breech loading designed to fire a number of lead pellets or shot in one charge.
Carbine – s short barrel rifle, having a barrel not longer than 22 inches and it is designed to fire a single shot through a rifled-bore, either semi-automatic or full automatic, for every press of the trigger.
.22 – minimum caliber - .19 - .18 – if only used as toys, could not be considered as firearm.
barrel of any firearm - Possession of any part of a firearm is considered a violation of illegal possession of firearm (SCRA Dec. 11, 1992).
FIREARM: IN ITS GENERAL CONTEXT
Firearm is any weapon that uses gunpowder to fire a bullet or shell. Generally, the term is used for light firearms, such as rifles, shotguns, and pistols. They are often called small arms. Heavier firearms are generally referred to as artillery.
Mechanism
Any firearm, large or small, has four essential parts:
1. Barrel – It is a long tube. It may be smooth, as in a shotgun, or with spiral grooves on the inner surface, as in a rifle.
2. Chamber - It is a widened hole at the breech (rear) end of the barrel. It holds the cartridge (explosive charge).
3. Breech mechanism - The breech mechanism closes the rear end of the barrel, holding the cartridge in the chamber.
4. Every up-to-date firearm has some way by which the breech can be opened for loading and locked for safety in firing. Artillery uses screw plugs or breechblocks. Machine guns, rifles, and other small arms usually have a metal cylinder, or bolt, that is locked when the gun is fired, and drawn back to eject (force out) the empty cartridge case and to reload.
5. Firing mechanism - The firing mechanism may be electric, as in some large artillery pieces. In small arms, a spring drives a pointed firing pin through the breech bolt against a sensitive primer in the cartridge. The firing pin is cocked (drawn back) against a hook called the sear. When the trigger is pulled, the sear releases the firing pin, which in turn leaps forward to strike the primer. A jet of flame from the primer ignites the rest of the powder, forming a gas. This explosive gas propels the bullet from the barrel.
HANDGUN/SHORT ARMS
1. Pistol – a handgun that is magazine feed. It is said that pistols were invented in the Italian town “PISTOIA.” Hence, the name pistol – arrived in Britain about 1515 as German import.
2. Revolver – A handgun with a corresponding cylinder that revolves before the barrel which consist of different chambers.
ORIGINS OF FIREARMS
BERTHOLD SCHWARTZ – a German monk, and Roger Bacon, an English monk – are both credited with gunpowder invention.
* Most reference books credit Roger Bacon, English monk and scientist, with the invention of gunpowder in 1248, and Berthold Schwartz, with the application of gun powder to the propelling of a missile in the early 1300’s. This powder was that we now call “black powder”.
1118 – Moors used artillery against Zaragoza. Early manuscripts tell o fseveral Moorish campaign in which artillery was used all dating prior to Bacon and Scwartz.
1245 – Gen. Batu, the Tartar leader used artillery in Liegnitz when he defeated the Poles, Hungarians and Russians. * It is also often stated that gunpowder was first invented by Chinese were aware of gunpowder and its use as a propellant long before its advantage became recognized in Europe. It may also assume the Arabs with their advance knowledge of chemistry at that time.
1247 – one of the earliest recorded uses of firearms in warfare was that o fan attack on Seville, Spain. 1346 – Cannons used by King Edward III of England at Crecy
1453 – Mohammed II of Turkey in his famous conquest of Constantinople.
1500 AD - French Artist LEONARDO DA VINCE as can be gleaned in his sketch of steam powered cannon to his primitive wheel lock firearm.
* First firearms were inefficient, large and heavy and were not capable of being carried by an individual soldier hence; the development of cannons preceded that of small arm weapons by almost 50 years.
Stages of development of man’s weapon:
> STONES > CLUBS > KNIVES > SPEARS AND DARTS > SLINGSHOTS TO HURL OBJECTS > BOWS AND ARROWS > CROSS-BOWS >GUNS > MISSILES
Contributors in Firearms Development
Col. Calvin H. Goddard, Md., OS, U.S. Army – Father of Modern Ballistics
Horace Smith – Founded the great firm Smith & Wesson and pioneered the making of breech-loading riffles. Daniel B. Wesson – An associate or partners of Smith in revolver making.
John M. Browning – Wizard of modern firearms and pioneered the breech loading single shot riffle. John T. Thompson – Pioneered the making of Thompson Sub-machine gun.
David “Carbine” Williams – maker of first known carbine. Alexander John Forsyth – Father of the percussion ignition. Elisha King Root – Designed machinery of making Colt firearms. Eliphalet Remington – one of the first riffle makers.
John Mahlon Marlin – founder of Marlin Firearms Company.
James Wolfe Ripley – Stimulated the development of the Model 1855 riffled-musket.
Samuel Colt (1814-1862) - of Hartford, Connecticut, produced the first practical revolver bringing it to what most gunsmiths would agree was its perfect form in the Colt Army 1873 model, which became famous for its .45 caliber. Other manufacturers followed Colt’s lead: Remington and Smith and Wesson in the US., Adams and Scott-Webley
in BRITAIN, Star, Luger, Browning and Beretta on the CONTINENT, until revolvers were in used in every part of the world.
Henry Derringer – He gave his name to a whole class of firearms (Riffles and pistols) John C. Garand – Designed and invented the semi-automatic US Riffle, Cal. .30 MI Oliver F. Winchester – one of the earliest riffles and pistol makers.
John Dreyse (1841) - Invented a breech-loading infantry rifle, the so called needle gun because of its long sharp firing pin.
Carl Walther (1866) - Develop a reliable small caliber automatic Pistol.
Paul Withelm Mauser (1871) - Produced parts of the rifle which had been adopted by the German government. Sergei Mossin (1891) - Designed the Russian Service rifle.
Kijiro Nambu (1904) - An army gun designer whose design was first produced by the Kayoba factory. Charles Dorchester & George Sullivan (1950) - Formed the Armalite business.
IMPORTANT DATES IN FIREARMS HISTORY
1313 – Gunpowder as a Propellant. The age of gunpowder began with its first use as a propellant for a projectile. Such use has been recorded as early as 1313.
1350 – Small Arms. Gunpowder was first used only in cannons. It was in the middle of the 14th century that portable hand
firearms were introduced. These guns were ignited by a hand-held hot wire or lighted match.
1498 – Riflings. The first reference to riffled barrels appeared. Although it’s important as an aid to accuracy was recognized by some, it was a year after before riffling was generally used.
1575 – Cartridge. Paper cartridge combining both powder and ball were developed. This greatly speeded loading and reduced the hazards of carrying loose powder.
1807 – Percussion System. The discovery of Forsyth in 1807 that certain compounds detonated by a blast would be used to ignite the charge in a firearm, for the basis for all later percussion and cartridge to come into general use.
1845 - Rimfire Cartridge. In France, Flobert developed a “bullet breech cap” which was in reality the first rim fire cartridge. 1858 – Center fire Cartridge. The Morse cartridge o f1858 marked the beginning of the rapid development of the center
fire cartridge.
1884 – Automatic machine-gun. Hiram Maxim built the first fully automatic gun, utilizing the recoil of the piece of load and fire the next charge.
1885 – Smokeless Powder. In France, Vieille developed the first satisfactory smokeless powder, a new propellant which not only lacked the smoke characteristic of black powder, but also more powerful.
MECHANISMS OF FIREARM ACTION
Generally, the principles involved in all firearms action are the same. When the firearm is cocked and ready to fire, a pull on the trigger will cause the firing pin of the hammer to hit the percussion cap of the cartridge in the firing chamber which is aligned with the rear portion of the barrel. The hit by the firing pin on the percussion cap will cause generation of a sufficient heat capable of igniting the primer.
The primer will in turn ignite the gunpowder or propellant which will cause evolution of gases under pressure and temperature. The marked expansion of the gases will force the projectile forward with certain velocity.
Owing to presence of the rifling at the inner wall of the bore, the barrel offers some degree of resistance to the projectile. In as much as the riffling is arranged in a spiral manner, the projectile will produce a spinning movement as it comes out in the muzzle.
Together with the bullet passing out of the barrel are high pressure heated gases, unburned powder grains with flame and smoke.
During explosion, there is a backward kick of the firearm which in automatic firearm cause the cocking and the cartridge cause thrown out by the ejector. The backward movement is called recoil of the firearm.
RIFLING
Rifling refers to spiral grooves that have been formed into the barrel of a firearm. It is the means by which a firearm imparts a spin to a projectile to gyroscopically stabilize it to improve accuracy. Most rifling is created by either cutting with a machine tool, pressed by a tool called a "button" or forged into the barrel over a "mandrel". The grooves are the spaces that are cut out, and the resulting ridges are called 'lands'. These lands and grooves can vary in number, depth, shape, direction of twist ('right' or 'left'), and 'twist rate' (turns per unit of barrel length). The spin imparted by rifling significantly improves the stability of the projectile, improving both range and accuracy.
It consists of the number of the helical grooves cut on the surface of the bore, it includes the lands and grooves are running parallel with one another concentrically.
* Sporting Rifle
As a bullet is fired from a rifle, grooves in the interior of the barrel cause it to spin. The spinning motion stabilizes the bullet and increases its distance and accuracy. This illustration shows a modern hunting rifle and highlights its main components.
Take Note:
Recent developments - The grooves most commonly used in modern rifling have fairly sharp edges. More recently, polygonal rifling has become popular, as it seems to produce better accuracy due to the fact that it does not damage the bullet as badly as conventional rifling. Polygonal barrels also tend to have longer service lives because the reduction of the sharp edges of the land reduces flame erosion. Higher velocities may be generated due to a reduction of friction and an improvement of the gas seal between the bullet and barrel. A disadvantage of polygonal rifling is that if simple lead bullets are used, lead from the bullet tends to accumulate in the barrel (called leading) resulting in a dirty barrel, poor accuracy, and if the leading becomes severe, excessive chamber pressure which could cause a barrel or locking failure. Polygonal rifling is currently seen on most pistols from GLOCK and Kahr Arms.
CALIBER OF THE FIREARM
The caliber of the firearm is the diameter of the bore of the barrel measured from land to land in rifled firearm. It is expressed in inches or fraction of an inch by the American and English manufacturers and millimeters or in centimeters there by manufacturers in Continental Europe.
THE RIFLE
The rifle, invented about 1500, had spiral grooves in the barrel that made it more accurate than any previous firearm. Smokeless powder was developed in the 1800's. Breechloading systems replaced dangerous muzzle loading. Many improvements since have resulted in high-powered firearms.
Rifle is a gun with spiral grooves in its long barrel that spin the bullet as it is shot. Rifles are usually held against the shoulder when firing. Soldiers use rifles in battle. People also use rifles to hunt game and to compete in shooting matches. The parts of a rifle - All rifles have four basic parts:
(1) the barrel,
(2) the stock, (3) the action, and (3) the sights.
How a rifle works. A rifle is ready to be fired when a cartridge has been fed into the firing chamber. Then the rifle is aimed and the trigger squeezed. The rifle's hammer or firing pin strikes the rear end of the cartridge and ignites the primer. The primer in turn ignites the propellant powder in the cartridge. The powder burns rapidly, creating pressure that drives the bullet down the barrel.
The rifling in the barrel makes the bullet spin. Without spin, a bullet would not stay pointed forward in flight, but would tumble over and over. The spinning motion increases the accuracy of a bullet.
Kinds of Rifles
Rifles are classified by:
type of action: (manually operated, automatic, or semiautomatic);
the name of the designer or manufacturer (for example, Remington or Winchester); or
caliber. Caliber may refer to the inside diameter of the barrel or the diameter of the bullet. The caliber is measured in millimeters or in decimal fractions of an inch.
There are three kinds of repeating rifles with hand-operated actions-bolt-action, lever-action, and slide-action. These rifles have magazines (cartridge holders) that feed cartridges into the firing chamber.
The action on two other kinds of rifles-automatic and semiautomatic-is operated by forces caused by the burning of the propellant powder in the firing chamber.
1. Bolt-action rifles have an action that resembles a bolt used to lock a door. When the bolt on the rifle is pulled back, the used cartridge is thrown out and the hammer is cocked. When the bolt is moved forward, it pushes a new cartridge into the firing chamber.
2. Lever-action rifles are loaded by moving a lever under the breech down and back up. The down movement throws out the used cartridge and cocks the hammer. The up movement inserts a new cartridge into the firing chamber. 3. Slide-action rifles, also called pump-action rifles, are loaded with a back-and-forth movement of a rod and handle beneath the front part of the barrel. When the handle is pulled back, the breech opens and the used cartridge is thrown out. A live cartridge is inserted when the handle is pushed forward.
Automatic and semiautomatic rifles are used mainly by soldiers and police officers. When a rifle is fired, gas is formed by the burning powder in the firing chamber. The expanding gas drives the bullet out of the barrel. In most modern automatic and semiautomatic rifles, some of this gas operates the action. When a cartridge is fired, a fresh cartridge is moved out of the magazine into the firing chamber, and the firing mechanism is cocked.
The M16A2 is the automatic rifle used by the U.S. armed forces. It weighs 8.9 pounds (4 kilograms) when loaded with a 30-cartridge magazine. The M16A2 can fire one shot at a time, or three shots in a single burst. It uses a 5.56-millimeter cartridge.
Rifle cartridges are enclosed in a casing (metal covering) made of brass or steel. Cartridges vary in size according to the caliber of the rifle. The names of some cartridges include the year the cartridge was put into use. The .30-06 is a .30-caliber cartridge chosen for use by the U.S. Army in 1906. The classification of some cartridges includes the caliber and velocity (speed) of the bullet. The bullet from a .250-3000 cartridge has a velocity of 3,000 feet (910 meters) per second.
Take Note:
Modern rifles developed from the crude, muzzle-loading firearms of the 1400's. Rifling of barrels was invented in Europe about 1500. Smooth-bore firearms (weapons without rifling) could not be depended on to hit targets more than 100 steps away.
The jaeger rifle of central and northern Europe was the first accurate rifle. It was developed about 1665. German immigrants brought jaegers to Pennsylvania in the early 1700's and gave them new features, including longer barrels. The Pennsylvania-made Kentucky rifle developed from the jaeger. Some Kentucky rifles were used in the Revolutionary War in America (1775-1783).
Rifles used round bullets until the 1850's, when more accurate Minie bullets became popular. Minie bullets had hollow bases and pointed tips and were used in the U.S. Civil War (1861-1865). Improvements of the late 1800's included repeating rifles, smokeless explosive powder, and jacketed bullets, which have a tough metal cover over a lead or steel core.
THE HANDGUN:
Handgun is a firearm that can be operated with one hand. Other types of guns, such as rifles and machine guns, require the use of both hands, a tripod (three-legged stand), or a shooting rest.
Parts of a handgun (the frame, the grip, the barrel, the sights, and the action)
The frame is the main body of the gun that connects the other parts. The grip is the handle of the gun, and the barrel is the metal tube through which the bullet is fired. The lands and rifling (grooves) are alternating raised surfaces and channels inside the barrel. They cause the bullet to spin and thus make it travel in a direct path.
The shooter uses the sights to line up the handgun with the target. Some sights can be adjusted to help aim the gun more easily. All handguns made for target shooting have adjustable sights.
The action includes the main working parts of the handgun. It consists of such parts as the trigger, the hammer, and the cartridge chamber. The type of action determines how the handgun is loaded and fired. The action of every handgun includes a safety, a mechanism that prevents the gun from being fired unintentionally. The safety ensures that the gun fires when the shooter squeezes the trigger, but not, for example, when the gun is dropped to the ground.
Types of handguns - There are five main types of handguns: 1. single-action revolvers,
2. double-action revolvers,
3. single-action semiautomatic pistols, 4. double-action semiautomatic pistols, and 5. single-shot pistols.
Revolvers carry ammunition in chambers in a rotating cylinder. Most pistols are loaded with a magazine containing the ammunition. The magazine is a metal holder inserted in the gun's butt (thicker end).
Single-action revolvers typically hold six cartridges. An arm near the hammer rotates the cylinder one-sixth of a turn when the hammer is cocked. This movement puts a cartridge into line with the barrel and the firing pin (part that strikes the primer to fire the cartridge). After cocking the hammer, the shooter pulls the trigger. The hammer unlocks and falls, exploding the cartridge. The Colt single-action Army revolver, first produced in the 1870's, is the most famous firearm of this type.
