GEMINI CRIMINOLOGY ONLINE REVIEW AND TRAINING CENTER P E N E T E E A P Dr. MANUEL V JAUDIAN, LLB. PhD ETEEAP DIRECTOR NOTES COMPILED AND EDITED BY: PROF. HERMOGENES MALAGAMBA 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. 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. BALLISTICS THEORY 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. Pioneers in the study of force and projectiles: 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. 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. 3. Bulk Density - The ratio of the weight of a given volume of powder vs. the weight of the same volume of water. 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. 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.