Sources of Elements Commonly Found in Lead Based GSRs

Table 6.1 A list of some common lead alloys. Tank linings, coils, pumps, valves, lead lined pipes, car storage batteries, collapsible tubes, bullets, lead shot, insoluble anodes. Type metals, bearings, special casting alloys Grids of industrial storage batteries, tape to separate double glazing panes Car and aircraft bearings and bushings Solders, insoluble anode in electro winning of Zn, manganese refining Pipe and sheet in chemical installations Solders (tin cars, circuit boards), manufacture...

Nontoxic Shot

In the United States, lead shot has been recognized as posing a threat to waterfowl since 1874. Efforts to phase out lead shot began in the 1970s, but a nationwide ban on lead shot for all waterfowl hunting was not implemented until 1991. Canada and the United Kingdom instituted a complete ban on the use of lead shot in 1999 with France following in 2006. The first, and probably still the most common, alternative non-toxic substitute for lead was soft steel shot. Whilst soft steel shot is...

Penetration of normal window glass

Very low velocity steel balls (BB) will generally cause a very small hole, often no more than 0.1 (2 mm) in diameter, through the glass ejecting a large cone of glass (spalling) from the side opposite the impact print. If the cone is not uniform it can give an indication of the direction from which the shot was fired. For -4'' (5 mm) plate glass, this can happen at velocities as low as 200 ft s. For lead air-gun pellets which are soft and readily deformable, a velocity of over 400 ft s is...

Inadvertently pulling the trigger by contact with some object other than the trigger finger

This is probably the cause of more hunting accidents than all the other causes added together. There are numerous recorded cases of twigs snagging on the trigger of loaded shotguns and rifles, and I am sure that many of them are genuine accidents. Less likely are those incidents allegedly involving inquisitive dogs, rabbits twitching in game pockets and even shot pheasants landing on the trigger guard Case example Fingerprint expert inadvertently discharging a shotgun. It would be highly...

Range of firing estimations for nontoxic nonlead primers

In general, it has been noted that when estimating the range of firing from discharge residue dispersion, the results from non-toxic primers do not tally with results from lead based primers (Gundry and Rockoff). This is probably due to the quantity of partially combusted materials present as well as the higher organic content of non-toxic primer compositions. The fact that lead has a high specific gravity might also be a contributing factor. In very general terms, the spread of discharge...

Further Reading

Christiansson, B.A.C. and Wintzell, K.A. (1995) An audiological survey of officers at an infantry regiment. Scandinavian Audiology, 22, 147-52. Paul, D.R., Chai-lip and Marcus, T. (1979) Hearing in military personnel. Annals of the Academy of Medicine, 8 (2). Pelausa, E., Abel, S. and Dempsey, I. (1995) Prevention of hearing loss in the Canadian military. Journal of Otolaryngology, 24 (5), 271-80. Wenselman, L., Henderson, D. et al. (1995) Effects of Noise Exposure Race and Years of Service on...

References

Betz, P., Peschel, O. and Eisenmenger, W. (1994) Suicidal gunshot wounds - site and characteristics. Archiv fur Kriminologie, 193(3-4), 65-71. Federal Bureau of Investigation (1999) FBI Uniform Crime Report. Hudson, P. (1981) Multishot firearms suicide. Examination of 58 cases. American Journal of Forensic Medicine and Pathology, 2(3), 239-42. Introna, F. and Smialek, J.E. (1989) Suicide from multiple gunshot wounds ( American Journal of Forensic Medicine and Pathology, 10(4), 275-84....

Introduction

As a consequence of advances in analytical technology and limitations on the way in which suspect interrogation is carried out, there has been an increasing necessity for the courts of law to rely on expert testimony. Scientific proof has therefore become a necessity in reconstructing the sequence of events at a crime scene. Such 'scientific proof' covers a large range of disciplines varying in value from the indisputable to that of very dubious value. Data obtained in a forensic laboratory has...

Acknowledgements

In writing the second edition of this book I have been assisted by more people than I could begin to recount. Of these, a few deserve special mention. Quenten Ford not only for his invaluable help in formulating the outline of the original book, but also for his assistance in correcting the many typos that crept in. Barbara Scott for her help with the statistics and various formulae used in both editions. Dr James Hamby, Evan Thompson and Chris Trumble for all their help and advice in so many...

Life expectancy of individual stria

If a weapon' s bore is well maintained, kept clear of metal fouling, regularly cleaned and kept free of rust, it is probable that the individual striations in the bore will not change significantly during a weapon' s life. Practically speaking though, the constant evolution of its individual characteristics will, over time, cause a significant change in these marks. This evolution of individual characteristics can be so significant that whilst it is possible to match bullets fired one after the...

Philosophy

Factors such as the hardness of the materials, pressures produced, build-up of fouling and general debris mean that the striations found on fired bullets and cartridge cases will inevitably exhibit variations from shot to shot. It is thus an impossibility for two bullets or cartridge cases fired from the same weapon to have absolute concordance in their stria. Conversely, in bullets and cartridge cases fired from different weapons, there will always, due to the sheer numbers of stria present,...

Brief glossary

Mechanical mixture of potassium nitrate, sulfur and charcoal. Nitrated cotton, a form of nitrocellulose. Trade name for obsolete propellant containing 85 black powder and 15 gun cotton. Nitrated cellulose which forms the basis of all modern propellants. A method by which the burning rate of a nitrocellulose-based propellant can be controlled by physically altering the grain shape or addition of a surfactant or chemical. Modern alternative for black powder.

Muzzle energy

Muzzle energy is probably the most important property when dealing with ballistics. This figure gives an indication of the overall power of the bullet as it leaves the barrel and, as a result, an indication as to its wounding potential. Naturally, many other factors have to be taken into consideration when dealing with wound ballistics, but these will be dealt with at a later stage. Muzzle energy is the potential work energy possessed by the missile as it exits the muzzle. It is quoted in terms...

Miscellaneous Devices

Manufacturers are receptive to comments from hearing protection users. This has led to the development of new devices that are hybrids of the traditional types of hearing protectors. Because many people like the comfort of foam plugs but do not want to roll them in dirty environments, a plug is now available that is essentially a foam tip on a stem. This plug is inserted in the same way as a pre-moulded plug but without rolling the foam. This is often used but of very little use as an...

General Background Questions

This should not include any reference to forensic firearms examination unless it is to note that it is often misrepresented as ' forensic ballistics'. Ballistics includes internal ballistics, which is the behaviour of a missile within the barrel, external ballistics, what course the missile takes from the muzzle to the target, and terminal ballistics, the bullet's effect on the target. These matters seldom have any relevance to forensic firearms examination. Q5. What is the make model and...

Penetration of bulletresistant jackets and vests

One of the tasks the forensic firearms examiner is often called upon to perform is the testing and evaluation of bullet-resistant vests and jackets, generally called soft body armour. As this aspect comes within the realms of terminal ballistics, it would be a good point to review the subject. History. Body armour, in the form of metal plates, was widely used during the time of hand- to-hand combat with swords, knives and various bludgeoning instruments. With the advent of the crossbow and...

Faulty lock mechanism

Basically, all locks work on the same principle a spring-loaded rotating (as in a weapon with a hammer) or sliding (as in a bolt action weapon) hammer with a small notch cut in it called a ' bent'. Into this bent fits one end of a pivoting lever which is called the ' sear'. The other end of this lever either forms or is actuated by the trigger. When the lock mechanism is cocked, the sear contacts the bent and holds the hammer or striker in the cocked position until the trigger is pulled. The...

Inadvertently pulling the trigger

In general, this is very difficult if not impossible to prove one way or the other. Numerous cases are on record of a violent fight during which the person holding the weapon has been violently thrown back against a wall with a claimed inadvertent discharge of the weapon. Hundreds of tests have be carried out (B.J. Heard, unpublished work) using volunteers under controlled conditions to test the probability of this happening. In the majority of these tests, unless the trigger pressure is...

Range of Firing Estimations for Shotguns Introduction

As shotguns fire cartridges loaded with pellets, rather than a single missile, the range of firing can be estimated with considerable accuracy up to 20 or 30 yd. This estimation relies on the fact that the pellets do not fly through the air as a single cohesive mass, but begin to disperse as soon as they leave the muzzle. This dispersion is caused by air pressure within the pellet mass, forcing them apart. This action continues throughout the range of the pellets. One common misconception is...

Distribution of GSR Particles

During the firing of a handgun, the vast majority of these GSR particles exit, at great velocity, from the muzzle of the weapon and are projected away from the firer. In self-loading pistols, some of the remainder escapes from the ejection port to settle on the hand holding the weapon. In revolvers, the particles escape from the gap between the rear of the barrel and the front of the cylinder. Whilst this gap is somewhat further forward than the ejection port in self-loading pistols, the gases...

Frequency

Pitch is measured in frequency of sound vibrations cycles per second, called hertz Hz . A low pitch such as a deep voice or a tuba makes fewer vibrations per second than a high voice or violin. The higher the pitch of the sound, the higher the frequency. Generally, noise-induced hearing loss occurs at a pitch of about 2,0004,000 Hz. Young children, who generally have the best hearing, can often distinguish sounds from about 20 Hz, such as the lowest note on a large pipe organ, to 20,000 Hz,...

Determination of angle of entry

Due to the disintegration of tempered glass, it is unusual to find enough of the entry hole left intact to determine the angle of entry. Laminated glass does stay together and it is possible to make some approximation of the bullet entry angle. As the angle of impact increases, so does the length of the bullet hole. It should be noted that the length of the bullet entry site will only give a very rough approximation of the angle of entry especially as the energy transfer to the bullet entry...

Brief History of Propellants Introduction

Gunpowder, whether it is - black powder - , - nitrocellulose' or a - double-based powder', is a solid substance that, on combustion, is converted into a very large volume of gas within a very short period of time. Whilst nitrocellulose- based powders can be detonated, in small arms ammunition, they are merely propel-lants which on ignition produce a very large volume of gaseous material which propels the missile down the bore. During combustion, the rate of reaction is exponentially...

Identification of weapon type

Breech Ejector And Extractor

When a revolver is fired, the fired cartridge cases remain in the weapon until the weapon is manually opened and the cartridge cases are ejected. Unless all the rounds have been fired and the weapon has been reloaded, it is unusual to find fired cartridge cases from a revolver at the scene of a shooting incident. With fully automatic weapons and self- loading pistols, rifles and shotguns, the empty cartridge case is automatically ejected from the weapon after firing. Unless there is a...

Range of firing estimations on heavily bloodstained garments

Range Officer Vest

Whilst it may be possible to still see, under low-power microscopy, the unburnt propellant particles, the sooty deposit from close-range discharges may be completely obscured by the blood. In instances such as these, the only recourse is to use infrared IR photography. By use of various filters and different wavelengths of IR, the colour of the garment and the bloodstaining can be eliminated, leaving the sooty deposit. This can then be photographed, using IR-sensitive film, and compared to test...

Multiple Shot Suicides

Multiple-shot suicides engender controversy due to the misconception that it is impossible to inflict more than one gunshot upon oneself. Tied in with this mistaken belief of instant incapacity are fallacies such as 'the impact of the bullet would send you reeling backwards', 'the gun would fly out of your hand', and so on. Incapacitation can be divided into three major groups 1. Instant incapacitation. This can only result from a cessation in the functioning of the central nervous system via...

Case example

Another illustrative case on the use of X-ray photographs concerns the case of an old man who dropped dead on the streets of Hong Kong. There were no suspicious circumstances, but to ensure that no pacemakers or anything else was present in the body that could cause problems with the cremation, a standard X-ray was taken. It was at this stage that the shadow of a bullet was seen next to the spine. At the PM, no obvious bullet could be found, but on excavating some calcified material surrounding...

Ultrasonic Cavitation for Restoration

Cavitation is the formation of vapour bubbles in a liquid due to a very localized reduction in pressure. This can be observed in high-speed motor boat propellers where a stream of bubbles is created. The phenomenon is very similar to boiling where bubbles of vapour are formed due to a localized increase in temperature. Any metal object which is subjected to this cavitational effect will be surface etched. In pumps, high-speed propellers and pipes carrying high-velocity liquids, this can be...

Rifles

M16 Self Loading Carbine Parts

Rifle actions can be very roughly grouped into single shot, bolt action, self-loading and pump action. Single shot. In single- shot weapons, the barrel can be hinged to the frame, allowing the barrel to be dropped down for loading and unloading, or can have some form of breech block which either swings out, pulls back or slides down to expose the breech end of the barrel. Bolt action. In bolt-action weapons, a turning bolt slides in an extension to the barrel, which is basically the same system...

Unburnt and partially burnt propellant particles

Being much heavier than the carbonaceous material, the propellant particles can be found on the target at much greater distances. With low-powered microscopy, these particles can be located on the target at ranges up to 30 for a handgun and to over 48 for a rifle. With 30 being the approximate arm length for an adult, the presence or absence of propellant particles can be extremely important in determining the sequence of events in a shooting case. Factors influencing the quantity of this...

Hearing Protectors

Hearing protection devices decrease the intensity of sound that reaches the eardrum. They come in two basic forms earplugs and earmuffs. Properly fitted earplugs or muffs reduce noise 15-30 dB. The better earplugs and muffs are approximately equal in sound reduction, although earplugs are better for low-frequency noise and earmuffs for high-frequency noise. Simultaneous use of earplugs and muffs usually adds 10-15 dB more protection than either used alone. Combined use should be considered when...

Appendix Important dates in the History of Firearms from

The first record of the actual use of gunpowder in Europe is 1247 a statement by Bishop Albertus Magnus in 1280 that it was used at the Siege of Seville in 1247. Roger Bacon gives an account of gunpowder in his Opus 1267 Majus Actually, his account was written in cryptic form. See T. Explosives Pelican Books, 1942 . Hand cannon had appeared in the field of battle during the 1364 Handguns were known in Italy in 1397, and in England they 1375 appear to have been used as early as 1375. The first...

Hearing Loss

It is generally accepted that a continuous noise level of 85 db decibels is the maximum safe level for long-term exposure to steady noise level within the frequency range of about 600-1,200 Hz. The very brief gunfire noises are another matter. Leading hearing specialists stipulate that about 150 db is the maximum peak limit for gunfire noises without impairment of speech perception and 140 db maximum without impairment of good hearing of music and the like. It should be noted that decibels are...

Bullet lubrication

Plain lead bullets must have some type of lubrication on their outside surface to reduce friction with the bore. Jacketed bullets do not generally require any form of lubrication. Lead bullet lubricant generally contains a mixture of vaseline, beeswax and graphite, although modern silicone based waxes are being used to a certain extent. In modern ammunition, this lubricant is held in a groove round the bullet, called a cannelure, which is generally located on the portion of the bullet inside...

Determination of bullet type

As the bullet passes down the barrel, the rifling will tear off small fragments of the bullet. Some of these fragments will remain in the bore and others will be blown out of the bore by the gases following the bullet. Some of these fragments do, however, remain attached to the bullet in the form of sub-microscopic pieces of swarf. As the bullet passes through any material, whether it is human flesh, fabric or wood, these fragments are often transferred to the medium through which it is...

Bullet materials

Modern ammunition comes with a bewildering variety of bullet profiles, materials and construction to cater for every conceivable circumstance. To attempt to cover all the available varieties is beyond the scope of this book. The following, however, covers the basic types of bullet which may be encountered. In small arms ammunition, bullets are either jacketed or unjacketed. Whilst unjacketed bullets can be made from all manner of materials, the most common by far is lead. The lead will be...

Accidental Discharge Failure of the safety mechanism

One very common fault in shotgun lock mechanisms of the old external hammer type involves a faulty 'rebound safety'. In this type of weapon, there is an additional bent in the form of a hook rather than a notch called the 'half cock' or 'rebound bent'. As the bent is hook shaped, the sear is firmly locked into place and it should not be able to manually push it forward or to pull the sear out of contact with the bent via the trigger. When in this half-cock or rebound position, the only way of...

Appendix Commercial and General Abbreviations for Bullet Configurations

ACC Accelerator - sub-calibre bullet fitted into conventional cartridge with a plastic sabot. ACP Automatic Colt Pistol. Used as a designation for cartridges designed specifically for self-loading pistol cartridges i.e. 0.380 ACP, 0.45 ACP . Can also be in lower case i.e. 0.380 acp or 0.45 acp . AP Armour-piercing bullet usually with a tungsten core. API Armour-piercing incendiary. As above but with the addition of an incendiary pellet in the nose. BRPT Bronze point. Bronze insert in tip...

Fluted Annular Ringed Helical Perforated and Oversized Chambers

Fluted, annular ringed, helical and perforated chambers exist in a number of modern weapons and can assist in identifying both class and individual firearm characteristics. Cutting grooves in a weapon chamber to improve the weapon' s functioning was first proposed as early as 1914. This was via a patent issued to Giovanni Angelli for various chamber modifications designed to retard and accelerate the extraction of a fired cartridge case. However, it was not until 1920 that the German Mann 0.25...

Event

The true pinfire cartridge emerged. 1 840 It was not until 1840 that we definitely found a breech- 1840 loading needle gun cartridge patented Wm. Bush, Pat. No. 8513 . The Brunswick rifle superseded the Baker model. 1840 Duelling declined in England after 1840. 1 840 The period of decadence of duelling was noticeable for the 1840-1850 production of rather short-barrelled pistols. A few service arms were converted to the percussion cap 1842 system in 1839, and it was officially adopted in 1842....

The Use of Xray Photography

The use of X-rays in the investigation of gunshot wounds can be invaluable to the forensic investigator for a variety of reasons and can help to 1. determine whether part or all of the bullet is still within the body 2. locate the exact position of the bullet 3. locate and determine the type and calibre of bullet where the bullet cannot be surgically removed 5. determine the position of all the pellets and wads in shotgun wounds prior to surgery. In numerous cases that I have dealt with, a...

Ignition of primers in a fire

As far as spontaneous combustion of the priming compound is concerned, the flameless ignition temperature of small arms priming compounds is generally in the region of 190-260 C. This is considerably lower than the ignition temperature for most small arms propellants, which is in the region of 350 C. It can be assumed, therefore, that during a fire, the first thing to spontaneously ignite will be the primer which will, in turn, ignite the propellant. Such ignitions are virtually harmless as the...

Other alternatives to lead

The list of other materials used or under review is exhaustive, and many more will almost definitely follow in the future. At present, the following are just some of those either used or currently being considered 1. soft steel often copper coated to reduce corrosion 2. iron-scrap tungsten Hevi-Steel 6. tungsten-iron-bronze Remington HD Shot 13. - ungsten-tin-iron-nickel Hevi-Shot 14. nitro-steel zinc galvanized steel - Remington. A comparison of the various densities for some of the non-toxic...

Deflection of bullet by glass

Austria Gun Proof Marks Bolt Action

Heard, unpublished work with various calibres of weapon fired at laminated windscreen glass held at varying angles has indicated that there is very little deviation of the bullet from its intended path. These can be conveniently illustrated by the following table Table 4.6 Table 4.6 Deflection of bullet from intended path at three different impact angles. Table 4.6 Deflection of bullet from intended path at three different impact angles. A very limited number of tests...

Ferrozine Spray

45acp Ballistics

In armed robbery incidents where no shot has been fired, it is often necessary to demonstrate a link between the suspect and a recovered weapon. As GSR particles will not be present on the hands, the only way this can be effected is through the detection of any metal traces which may have been transferred from the weapon to the hands. The quantity of metal traces transferred from the weapon to the hand is extremely small and probably below the threshold for analytical detection by conventional...

Identification of Calibre from the Bullet Entry Hole Introduction

Bullet Identification Markings

In skin and fabrics, it is, unless a wadcutter-type bullet is used, all but impossible to determine the calibre of a missile from its entry or exit hole. Wadcutter bullets, as discussed earlier, are intended for target practice. As such, they are designed to cut a clean hole through the target to facilitate the determination of the shooter' s accuracy. When round-nosed or even hollow-point bullets are used, the hole produced by the bullet is very much smaller than its calibre. In skin, this is...

Formation of stria

Bullet Striations

During the firing of a weapon, the individual stria are transferred from the hard surface of the weapon on to the softer surface of the bullet or cartridge case during the firing. As the tremendous pressures build up during the first few moments of firing, the base of the bullet swells to fill and so obturate the weapon' s bore. As it passes down the barrel, the minute irregularities in the bore form longitudinal scores or striations down the length of the bullet. Some of these are obviously...

Oversized chambers

The German FG42 Paratroop rifle 42 and some issues of the MP44 make use of the same principle as a fluted chamber in that they have chambers that permit escape of gases around the cartridge case. These chambers, however, are not conventionally fluted, but are of larger diameter for approximately the rear half of the chamber. This allows the gases to escape into this area, thus equalizing the pressure and easing extraction. A list of some of the more current weapons using these chamber markings...

Bullet base configuration

Cannelure Parts Bullet

Whilst most small arms bullets have a base which is the same diameter as the body, long-range rifle bullets have the rear section of the bullet tapered. This is to reduce base drag and is referred to either as a boat-tailed bullet US nomenclature or a streamlined bullet British nomenclature . These bullets are generally military, but can also be encountered in commercial ammunition. A heeled bullet is one in which the rear portion of the bullet, which fits into the cartridge case, is reduced so...

Individual characteristics on cartridge cases

The parts of a weapon which imprint class characteristics on the fired cartridge case have, of course, been individually manufactured. The manufacturing process involves cutting, drilling, grinding, hand filing and, very occasionally, hand polishing. Each of these processes will leave individual characteristics in much the same way as the boring process, which is the initial step in making a barrel. An example which conveniently illustrates the production of individual characteristics would be...

Sample Collection

Gunshot Residue Retention The Hands

The methodology for sample collection for GSR analysis is simplicity itself. The most commonly used technique uses a 1 x l cm strip of double-sided adhesive tape stuck onto a thin acetate strip. The acetate strip allows the adhesive surface to be conveniently manipulated without any fear of contact with the sampler's hands. One of these tapes is used to take samples from each of the four areas as illustrated in Figure 6.3. During the taking of the samples, the skin must be stretched as much as...

How We Hear

Sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum. The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones are called the malleus, incus and stapes. The bones in the middle ear amplify, or increase, the sound and send the vibrations to the snail-shaped cochlea, or inner ear. The cochlea is a fluid-filled organ with an elastic membrane that runs down its...

External Ballistics Introduction

External ballistics is the study of the missile -s flight from when it leaves the muzzle until it strikes the target. It is an extremely complicated subject and before the advent of powerful desktop computers, the calculations were laborious and time consuming, requiring the use of many mathematical tables. With modern computers and ballistic programmes, it is now possible to calculate the most complex trajectory equations with just a few key strokes. The two main factors which affect the...

Fluted chamber

Fluted Chamber

Fluted chambers are longitudinal flutes which are deeper at the forward end of the chamber and taper off towards the rear. These allow the gases produced on firing to flow back over the outside of the cartridge case during firing. This counters the internal pressure and ' lubricates' the case, thus facilitating the extraction process. This is utilized in blowback and delayed blowback weapons where pressures are relatively high, thus making extraction difficult Figure 4.18 . Figure 4.18...

Penetration of laminated glass

When struck by a bullet, laminated glass which consists of two sheets of glass bonded together with a plastic film will first bulge away from the site of impact. This causes a series of radial cracks. As the glass continues to bulge, concentric cracks are produced, the quantity of which are determined by the energy given up by the bullet to the glass Salferstein, 1982 . The quantity of crushed glass round the periphery of the entrance hole is also a function of the energy given Easily deformed,...

Discharge due to inappropriately low trigger pressure

For target use, trigger mechanisms are often 'tuned' to give a smoother, lighter trigger pull. It is not unusual to find target pistols and rifles with trigger pulls in the region of 1 lb. Accepted commercial and military trigger pulls vary tremendously, but generally, the following could be considered as acceptable Whilst a 'tuned' trigger pressure as low as 1 lb may be totally acceptable in the very specialized arena of a target shooting competition, in other circumstances, it can be...

Theory of recoil

As seen earlier, the velocity of the bullet leaving the weapon or the velocity of the recoil of the weapon is calculated by the following formulae M is the mass of the gun or bullet F is the force in pounds, and T is the time during which it acts. During the period which this force is acting on the bullet, it is, therefore, also acting with an equal degree of force on the gun. If the velocity of the bullet is v, the mass of the bullet m, the rearwards velocity of the gun V, the mass of the gun...

Range of firing estimation on badly decomposed bodies BJ Heard unpublished paper

Decomposed Bodies

Estimating the range of firing on a badly decomposed body can, unless a shotgun has been used, prove to be extremely difficult. The putrefying tissue either masks the presence of residues or they are removed as the outer layers of skin slough off. A case where this problem was of considerable importance involved the shooting and subsequent dismembering of a young insurance sales woman. After being shot and then dismembered, the body parts were placed into several black plastic bags and dumped...

Purposeful eradication of individual characteristics

It is often assumed that the last part of the rifling to touch the bullet before it leaves the barrel produces the only stria of any significance. In part, this is true as the last part of the bore does have the ability of erasing any stria which came earlier. It is also true that if the marks made nearer to the breech were deeper than those at the muzzle, then they will not be erased. There have been many instances where the last few inches of a barrel have been sawn off in an attempt to...

Scorching

Norma Bullet Types

This is caused by the incandescent gases as they emerge from the muzzle of the weapon. Although they initially leave the barrel at a temperature of around Figure 5.9 Discharge residue deposits for various types of ammunition at the same range a Winchester b Sellior and Bellot c Norma d Rem UHC. Figure 5.9 Discharge residue deposits for various types of ammunition at the same range a Winchester b Sellior and Bellot c Norma d Rem UHC. Figure 5.10 Discharge residue patterns for the same ammunition...

Shotgun ammunition

Shotgun ammunition is once again a confusing subject with the smaller calibres being referred to by the approximate bore diameter, that is, 0.22, 9 mm, 0.410. Once past 0.410, the calibre changes to a bore' or if using the American nomenclature gauge' size where the bore is the number of lead balls of the same diameter as the inside of the barrel which weighs 1 lb. Thus, a 12- bore shotgun has a barrel diameter of 0.729 and 12 round lead balls of 0.729 diameter weigh exactly 1 lb. It should be...

Ferrozine Test

How do you know that the results obtained from this test were not caused by a kitchen knife, or a knife fork and spoon A39. Firstly, most kitchen utensils are made from stainless steel or are nickel or chromium plated, none of which gives a positive result to this test. In addition, this whole test relies on the interpretation of the visualized marks on the hands. The examiner will, therefore, have to prove beyond reasonable doubt that the marks observed were those from a weapon and not...

Recoil energy

All the above is concerned with the velocity of the gun's recoil, which tells us very little about the actual force, or more correctly, the energy of the recoil. The energy of the recoil is calculated by use of the formula The kinetic energy KE of the recoil, or the recoil energy, gives us a much clearer picture of the actual forces involved. The recoil energy of a weapon and, for that matter, the kinetic energy of a bullet are calculated in exactly the same way and are measured in foot pound...

Glossary

Abbreviation for Automatic Colt Pistol. Used to designate calibres designed for use in Colt self-loading pistols. The mechanism of a firearm. A design for a semi-automatic firearm wherein the breechblock is stationary and the barrel moves forward by gas pressure to open and eject the cartridge and re -cycle the action. A design found in semi-automatic and automatic firearms where the inertia of some component, usually supplemented with a spring, is the main locking force and no mechanical...

Weapon Types and Their Operation

Revolver Mechanism

Terrible confusion exists as to what is a pistol, revolver, self-loading pistol and automatic. This is very basic firearms nomenclature, but it is often wrongly applied. The use of the correct term is absolutely essential if any credibility is to be maintained. This chapter attempts no more than to carefully explain the correct usage and, where they exist, alternatives which one might encounter. There are three basic types of handgun single shot, revolving and self-loading pistols. Such exotica...

Mathematical Proof of Striation Matches Introduction

This is a difficult subject to comprehend due to the statistics involved. As such, it is often, when dealing with questions on the subject in court, glossed over with such comments as 'statistically it can be shown, but as I am not a statistician' or ' empirical studies have shown' or even ' a match is one which exceeds the best known non-match'. But, how large does an empirical study have to be before it can be determined that a match between two bullets is beyond reasonable doubt Does an...

Appendix Powder Burn Rate

This powder burn rate chart is by no means a complete list of powders available and is intended for reference only Table 7.A.1 . Powders may move up and down the list as new powders become available or as other powders are discontinued. Powder burn rates can and do change from batch to batch, or as manufacturers change product specifications. No. 1 on this chart is the fastest powder, with powders becoming progressively slower as you move down the list to No. 173.

Rifling

Rifling is the term given to the spiral grooves cut into the bore of a barrel which impart a stabilizing spin to the bullet. This spin keeps the bullet travelling in a point-first direction and lessens any tendency for it to depart from its straight line of flight. As such, this was a very significant event in the evolution of firearms. Some writers assign the invention of spiral-grooved barrels to Gaspard Kollner, a gunmaker of Vienna, in the fifteenth century. Others fix the date at 1520 and...

Estimation of calibre from Xrays

Evan Thompson Firearms

Whilst X-rays can be used to accurately locate a missile, they cannot be used to precisely measure the calibre of a missile as all X-ray images, by virtue of the way they are taken, are magnified to some degree. As the distance from X-ray plate to the missile increases, so does this magnification effect. These problems can be offset by taking two X-ray photographs of the body, one face on and one side on. These can then be used to estimate the depth of the missile in the body. A number of...

Handbook of Firearms and Ballistics

Examining and Interpreting Forensic Evidence A John Wiley amp Sons, Ltd., Publication This edition first published 2008, 2008 by John Wiley amp Sons Ltd Wiley-Blackwell is an imprint of John Wiley amp Sons, formed by the merger of Wiley's global Scientific, Technical and Medical business with Blackwell Publishing. Registered office John Wiley amp Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 9600 Garsington Road, Oxford, OX4 2DQ, UK 111 River Street, Hoboken, NJ...

Linese and USSR ammunition

APPENDIX 2 GSR RESULTS FOR CHINESE AND USSR 6.72 x 25 mm GSR Results cont. N.B. If conflicting results have been obtained for cartridges with the same headstamp, the number in brackets indicates the number of samples with that composition. N.B. If conflicting results have been obtained for cartridges with the same headstamp, the number in brackets indicates the number of samples with that composition. Other calibres of Chinese ammunition Other calibres of Chinese ammunition

Bullet types

Originally, a bullet was a simple lead sphere which worked well with the smooth-bored muzzle loading early firearms. The sphere, however, has a very poor ballistic shape, and it rapidly loses velocity. With the introduction of rifling came the ogival-shaped bullet basically the profile of a pointed arch which had a length in excess of twice its diameter. This provided an easily stabilized bullet with excellent accuracy and a good shape for penetrating the air i.e. good ballistic profile .

Recovery methods for fired bullets

If a weapon has been recovered, it will be necessary to compare fired ammunition from this weapon with fired ammunition recovered from the scene. Obtaining a series of test cartridge cases from a self-loading pistol presents little difficulty as they merely have to be picked up. Obtaining fired bullets in a near pristine condition is, however, a little more difficult. In the past, cotton waste or wadding has been used, but this material can be quite abrasive to soft-lead bullets especially...

Brief History of Firearms Early hand cannons

1517 Wheel Lock

The earliest type of handgun was simply a small cannon of wrought iron or bronze, fitted to a frame or stock with metal bands or leather thongs. These weapons were loaded from the muzzle end of the barrel with powder, wad and ball. A small hole at the breech end of the barrel, the touch hole, was provided with a pan into which a priming charge of powder was placed. On igniting this priming charge, either with a hot iron or lighted match, fire flashed through the touch hole and into the main...

Methods Used for Removal of Serial Numbers

It is often the case that stolen weapons will have the serial number obliterated in an attempt to hide the weapon 's origin. Methods of obliteration generally fall into the following categories This is simply removing the number by hand filing or grinding with a high-speed carborundum grinding wheel. This is often followed by polishing and then over-stamping with a new number. Handbook of Firearms and Ballistics Second Edition Brian J. Heard 2008 John Wiley amp Sons, Ltd. This merely involves...

Basic Methodology Used in Comparison Microscopy Introduction

It has been quoted Walls, 1968 that up to 25 of the stria in a non-match and in excess of 75 of the stria in a match will show concordance. Such a degree of accidentally matching lines is exceedingly high and has not been supported by personal experience. There is no dispute, however, that out of the thousands of lines present in any one comparison, a number must, by pure chance alone, show agreement. When carrying out a microscopic comparison, the accidental agreement in a non-match must be...

Bullet performance and wounding capabilities

This is another of those subjects surrounded by myth and misinformation. In many ways, this is understandable as the number of factors influencing how a bullet reacts on entering a human body is so diverse as to make a scientific study of the subject virtually impossible. If the body were made uniformly from a material of constant density, it would be extremely simple to simulate the effects of a bullet. The body is, however, full of voids with a hard bone skeleton and is associated...

Degree of shot dispersion

Benelli Raffaell Crio Choke Ret

The degree of dispersion of the shot is dependent on many factors, the most important of which are Cartridge type. The higher the pressure generated by the cartridge, the more the shot will be disrupted as it emerges from the barrel by the following gases. Whilst this effect is largely offset by the wads used in modern cartridges, it is a factor which does affect the dispersion of the shot. Wad type. The wadding in traditional shotgun cartridges consisted of an over-powder wad, a series of...

Appendix Trade Names

Trade name of Azanza y Arrizabalaga, Spain Manufactured copies of cheap Belgian pistols Trade name of spur trigger revolvers made by Hopkins amp Allen about 1885 Used by J.Stevens Arms Co. about 1882 Used by Hulbert Bros on Hopkins amp Allen revolvers about 1893 Manufacturer of Adams designed firearms 1864-1892 Spur trigger revolvers made by Harrington and Richardson about 1876 On revolvers sold by Meacham amp Co. 1880 On revolvers sold by Stoeger from W. Germany Trade name on revolvers made by...

Blackening

This is caused by carbonaceous material in the discharge residues mainly resulting from incomplete combustion of the propellant. It can also result from excessive quantities of bullet lubricant or even the bitumen sealant used between the bullet and cartridge case. It is composed mainly of amorphous carbon, although fine particles of partially burnt propellant can also be present. This effect really begins where scorching finishes and can be up to 10 in. 25 cm from the muzzle in rifles and 5...

Ballistic coefficient

The sectional density is not the only factor affecting the retardation the degree of velocity loss due to the air of a bullet, as the shape also plays a very large part. If the form factor i is inserted into the formula, the resulting figure is called the 'ballistic coefficient' of the missile and is the proportion of the bullet's diameter to its weight. The ballistic coefficient C is calculated by using the formula C ballistic coefficient w weight of bullet i form factor d diameter of the...

Accidental Discharge

Wound Ballistics

With the safety mechanisms employed in modern weapons, incidents labelled as 'accidental discharge' have to be treated with some scepticism. Basically, cases of accidental discharge have to be placed into one of five categories 2. discharge due to inappropriately low trigger pressure 3. failure of the safety mechanism 4. inadvertently pulling the trigger 5. inadvertently pulling the trigger by contact with some object other than the trigger finger. Figure 4.29 Basic lock mechanisms. SMLE, Short...

Ricochet Analysis Introduction

Projectile Ricochet

When a bullet strikes any surface, there is a critical angle at which the bullet will bounce off or ricochet from the surface rather than penetrate. After ricocheting from the surface, the missile will lose a considerable amount of its velocity anything up to 35 in test firings and, invariably, lose its stability. This is contrary to the popular belief that a ricocheting bullet will carry further than one fired at the elevation for maximum range. The actual degree at which a bullet will...

General wound ballistic concepts

Carbine Exit Wound

There are three concepts generally held by most as to the effect of a bullet striking a human being. The first is that the bullet 'drills' its way through leaving a small entry and an equally small exit hole. The second is that the bullet leaves a small entry hole and an enormous exit hole. The third is that when someone is shot by anything other than an air rifle, the impact is enough to lift the person off his feet and send him flying through the air. Basically, all three concepts are...

Methods of measuring barrel pressure

Homemade Guns And Homemade Ammo

Assuming that the weapon is in good condition and that the correct type of ammunition is being used, it is the pressure produced in the barrel which ultimately decides whether the bullet will either reach the muzzle, exit from the barrel at an acceptable velocity or destroy the weapon completely. Often weapons are received with reloaded or home- made ammunition and for safety sake, it is often necessary to determine whether the ammunition is in fact safe to fire. At other times, it is necessary...

Zinc sulphide

Table 2.12 A brief history of primer development. Swiss military primer US Winchester primer Potassium chlorate Antimony sulfide Glass powder Mercury fulminate Barium nitrate Antimony sulfide Picric acid Potassium chlorate Antimony sulfide Sulfur Mercury fulminate Antimony sulfide Barium peroxide TNT trinitrotoluene Mercury fulminate Barium nitrate Antimony sulfide Barium carbonate Potassium chlorate Antimony sulfide Lead thiocyanate TNT trinitrotoluene Mercury fulminate Barium nitrate Lead...

Brief History of Ammunition Introduction

Detenation Rim Fire

The first forms of ammunition consisted of loose powder, carried in a flask or horn, and various projectiles which were loaded into the barrel from the muzzle end. These early projectiles were often irregularly shaped stone balls or arrowlike objects. By the fifteenth century, ammunition had become fairly standardized and consisted of 'black powder' propellant a mixture of charcoal, sulfur and potassium nitrate , followed by some wadding, a spherical lead ball and further wadding to retain it...

Ammunition types

Small arms ammunition basically consists of a cartridge case, primer, propellant and some form of missile. There are really only three types of small arms ammunition in current production ' rimfire', 'centre fire' and 'caseless'. Rimfire ammunition consists of a short brass tube, generally 0.22 in. in diameter, closed at one end. The tube contains a charge of propellant and has a bullet at the open end. The closed end of the tube is formed into a flat head with a hollow rim which contains the...

Basic Concepts of Striation Matching Class characteristics

As explained in Section 4.2, the rifling of each weapon will possess a series of family resemblances which will be present in all weapons of the same make and model. Correctly called 'class characteristics', they relate to the number of lands and grooves, their direction of twist, inclination of twist, width and profile. Whilst these dimensions can be extremely useful in identifying the calibre, make and model of the weapon which fired a particular bullet, they cannot be used to individualize...

Accidental discharge of primers

Following on from the subject of primer sensitivity is the frequently mentioned possibility of cartridge cases exploding in the pocket through coming into contact with keys or change, and of cartridges exploding when dropped onto the ground. Experience and an extensive series of tests has shown this to be exceedingly unlikely. Both rimfire and centre fire cartridges have been repeatedly thrown with great force onto their base without the slightest effect. Cartridges have been dropped down...

Other instruments used in forensic firearms examination

Apart from the everyday instruments commonly found in any forensic laboratory, for example, microscopes, micrometers, and so on, there are a number of others which, although probably no longer in common use, one should be aware of. Rifling meter. In this instrument, the barrel of the weapon under examination is clamped to the bed of a lathe. Into the tailstock of the lathe is fixed a long steel rod, one end of which has a lead plug of the same diameter as the bore of the weapon. The other end...

Bullet wipe marks

Bullet lubricant, bullet case mouth sealant and gases, which have squeezed past the bullet on its passage through the bore, leave the outside of the bullet coated with a layer of black sooty material. As the bullet passes through an object, whether it be cloth, skin or some solid object, this black material is deposited on the periphery of the bullet entry hole. This black ring is often referred to as the 'bullet wipe' and, where no discharge residues are present, it is a very useful identifier...

Headstamps

This is a potentially a very important subject as it enables the determination of country of origin, whether it is of commercial or military manufacture, and if military, the date of manufacture. Whilst this may seem to be of minor importance, in cases involving terrorism, such information can be vital. This subject alone could fill several volumes, and many books have been written on the identification of ' headstamps'. The subject is dealt with more comprehensively in Section 2.6, but a few...

Determination of bullet type from entry hole

Determination of the calibre of bullet from the resulting hole and degree of concentric cracking can be made, although the variables make this a difficult task. In -aminated glass, the degree of concentric cracking is directly proportional to the amount of energy given up to the glass as the bullet passes through. The amount of energy given up by the bullet will depend upon the bullet calibre, its construction and velocity. The softer the bullet, the greater the deformation. The greater the...

Nontoxic and frangible bullets

Lead contamination of firing ranges, both indoor and outdoor, has been a continuing and serious problem. The US National Bureau of Standards claims that 80 of airborne lead on firing ranges comes from the projectile, whilst the remaining 20 comes from the combustion of the lead styphnate primer mixture. In the early 1980s, a concerted move was made towards eliminating this health hazard, especially at training facilities and indoor ranges. The first step in this process was to eliminate the...

Identification of GSR Particles Organic components

Recovery Hypo Fixer Silver

The quantity of organic compounds left over from the burning of the propellant is obviously vast in comparison to those from the priming compound. As a result, early attempts at detecting GSRs were directed towards the recovery and identification of the organic components. These included the identification of nitrites and nitrates in partially burnt propellant particles using chemical spot tests. One very popular test was the Walker test Walker, 1940 , which used desensitized photographic paper...

Cartridge cases

In the Western world, these are almost invariably made of brass with a 75 25 copper zinc alloy. Other materials including steel and plastic have been used, but not on any commercial basis. Aluminium-cased pistol ammunition has recently acquired some commercial success due to the cost saving of aluminium over brass. There are, however, a number of disadvantages. These include being non-reloadable and less robust than their brass counterparts. For large-scale users who do not wish to reload their...

Brief History of Forensic Firearms Identification Introduction

As with any evolving science, the exact origins of forensic firearms identification are shrouded in obscurity. Exactly when it was first noted that fired bullets from a given weapon possessed a certain number of equally spaced impressed grooves, all inclined in the same direction and at the same angle, and which were the same on every other bullet fired through that weapon, will probably never be known. Likewise, it will never be known when the next logical step was taken to compare the width,...

Problematical areas

Polygon Rifling

Damaged bullets, bullets fired through rusty barrels, bullet fragments and barrels with little or no rifling, all produce their own problems. Polygonal rifling, however, produces problems of a completely different type. The main difficulties with trying to match two bullets from a polygonal rifling are There are no sharp - edged rifling grooves it is extremely difficult to locate land and groove marks. The barrel is hammered on to a mandril there will be no reaming marks to replicate themselves...

Priming Compounds and Primers Introduction

A priming compound is a highly sensitive explosive chemical which, when struck by the firing pin or hammer of a weapon, will explode with great violence, causing a flame to ignite the propellant. This explosive chemical is often mixed with other chemicals which provide oxygen to assist in the production of the flame, a fuel to increase the length and temperature of the flame and ground glass as an abrasive to assist in the initial ignition of the explosive. In the realms of forensic science,...