Co

(A) A Section of a typical British Shotgun Cartridge (B) two fired i2-bore shotgun cartridges showing the effects of The pressure developed in the case on the left was high, while that developed in the case on the made of this latter substance are known as Nobeloy envelopes in Great Britain and Lubaloy in America. It should be noted that brass is an alloy of from 65 to 75 per cent, copper and from 35 to 25 per cent, zinc, and gilding metal an alloy of 85 to 95 per cent, copper and 15 to 5 per...

M

Machine Gun, Sub-, 23 Main Spring, 85, 87 Mann, 147 Mark, Skid, 139,140 Marks, Eje'ctor (see Ejector) Unaccountable, 123-126 Mars, 28 Martini, 20, 34 Mauser, 29, 166 Mayne, Captain, 184 Mechanical Stage, 129, 174 Metal, Gilding, 40, 41 Metallic Fouling, 160-163 Nitrates, 70 Mezzer, Dr. Otto, 203 Micrometer Eye-Piecc, 199 Microscope, Comparison, 131,132, 153, 154, Illumination for, 132, 172, 173, 175, 176 Stereoscopic, 173, 203 Military Rifles, 20 Moddite, 32

Procedure For Identification

I have now done my best to describe the various types of markings which may be found on a fired cartridge case and their sources of origin, and the next step is to consider how these facts can be utilised properly and correctly in the task of identifying some individual arm. If a cartridge case is found on the scene of a crime, and a pistol is found later which may have been used by the murderer, the procedure to be adopted in order to determine whether thecrime cartridge case marries the...

Service Revolver

The correspondence in the markings on the two caps is obvious The values which I have given for the respective muzzle velocities are those developed by cartridges of British manufacture in revolvers or pistols of normal barrel lengths. Different lengths of barrel will cause slightly different velocities, an increase in barrel length causing an increase in velocity while a short barrel causes a loss. But various foreign manufacturers load their cartridges to somewhat different ballistics, and...

The Forensic Microscope

The comparison microscope shown in Plate XXXIX was made specially for me by Messrs. W. Watson & Sons, and at my request it was kept as simple as possible. The result is that various movements not usually found on ordinary microscopes are included, while other movements have been deliberately omitted for the sake of simplicity. For example, there is no fine adjustment, as such is quite unnecessary for the low-power objectives which are used. On the other hand, there is both body and stage...

Caps

For all practical purposes the cap is an integral part of the cartridge case. In the vast majority of modern cartridges the cap is situated in the centre of the base of the case, and for this reason all such cartridges are termed Central-Fire cartridges. In -22 miniature rifle cartridges, however, the cap is in fact a part of the cartridge case, the whole of the base being the cap. These cartridges are fired by a blow on the edge of the base and on this account are known as Rim-Fire cartridges....

X

Seven grooves right-hand twist narrow lands and broad grooves. Used in all Webley revolvers. Smith and Wesson Type. Five grooves right-hand twist grooves and lands of equal width. Used in all Smith and Wesson revolvers except the -45 Model 1917, Harrington and Richardson revolvers, and Iver Johnson revolvers, but in no self-loader. In addition to the general principles adopted in these five main types there are other minor differences which may exist in rifling of the same type....

Selfloading Pistol

These two ca es were fired by the pistol of which the breech face is shown in Plate I. but they are different cases to the fired case shown in Plate I. The identity of the markings on all three cases fired by this pistol will be clear acid, while in black powder and many modern powders, including all British smokeless shotgun powders, they are alkaline with a view to checking the rusting effect of the cap composition. Then, as has already been stated, the...

Section Of Barrel

Section Central Fire Rsbot Cartridge

A sectional diagram of the apparatus used for measuring and the breech face of the action. The pressure is obtained by measuring the reduction in length of the crusher as has already been described. It will readily be understood that in order to obtain constant and comparable results it is essential that all possible sources of variation should be eliminated, and with this end in view everything connected with the measuring of pressures in shotguns in Great Britain was standardised in...

The Case of the Shot Cypriot Doctor

The upper row gives four different views of the fatal bullet This bullet must clearly have been fired through a very tight barrel, as the land engraving is very deep and heavily scored and reaches well above the top of the cannelure, while the striations caused by the groove engraving extend ail round the circumference of the bullet. The lower row shows four similar views of one of the test bullets which was fired from the suspect pistol. This bullet is of exactly the same mean diameter as the...

Types Of Firearms

FIREARMS which are used in crimes of violence can be divided into two main types Smooth-Bores and Rifled Arms. Both these types, especially the latter, can be subdivided into a number of varieties but the forensic problems which arise will generally fall into two main categories corresponding with the two main types, although there will sometimes be a certain amount of overlapping. It will, therefore, be convenient first to consider the two main types of firearms, and then the various...

The Identification Of Firearms Technique And Examples

IN the last two chapters it has been seen that the science of identifying individual firearms is dependent on the microscope. Now a microscope is by no means an easy instrument to use. There is a common belief that almost anyone can use a microscope with effect but like many common beliefs it is quite erroneous. In order to interpret correctly the result which the power of the microscope can convey it is essential that the investigator should master the correct technique. There are various...

W

Forensics Ballistics

E now come to a subject to which very little attention is normally paid, but a full and proper understanding of which is absolutely essential in forensic work. As has already been explained in the preceding chapter the explosive charge in any cartridge consists of two separate parts the Cap, and the Propellant, or Powder. The cap contains a small amount of sensitive composition which can be exploded by the degree of heat resulting from friction, or a blow. This composition is contained in a...

Bullets

In rifles, revolvers and pistols (other than shot pistols) the projectile consists of a single bullet. In the days of black powder and before the introduction of nitro powders the bullets were all made of lead. And since it was found that pure lead was rather soft and exhibited a tendency to strip in the bore of the weapon, bullets were usually hardened with small additions of tin or antimony. When nitro powders came into being, velocities were increased so much that leaden bullets could not...

The Left Lock of the same Gun in the rebound position

Owing to the scar tail being forccd up by the pressure of the wood of the stock the sear nose has been forced down out of the bent (see arrow) relative matter as has been seen, as a pressure which would be feeble in one cartridge would be violent in another.1 Gas, however, may also escape through a split in the rim of the cartridge or through a split in the side close to the base. The former may be a sign of violence, and the latter generally is such a sign. If the breech face does not fit...

C

Composition, 30, 44, 82, 83 Testing for Sensitiveness, 50 Caps, Bulleted, 19 Capsule, Cap, 30, 54, 68 Cartridge Cases (see Cases) Cartridges, Central Fire, 29 Rim Fire, 29, 30 Cases, Pistol, 28, 29 Cone, 16, 139 Chicago, 159 Chilled Shot, 37 Chlorate, Potassium, 82 Chloride, Potassium, 82 Sodium, 82 Choke, 71, 72, 73 Coated Shot, 38 Colt, 28, 140, 200 Combustion, 40, 45, 62, 63, 68, 69, 70 Non-Volatile Products of, 70, 71, 82 Comparison Microscope, 131, 151, 152, 153, 154, 174 Composite...

P

Penetration, Meaning of, in Microscopy, 149 Photographs, Composite, 131, 151, 152, 153, 154, 174 Powders (see Powders) Pistols, Saloon, 19 Toy, 19 Piston, 45, 46, 47, 48 Pitch, How Measured, 199, 203, 204 Plate, Lock, 93 Side, 93 Play, Trigger, 92 Pointolite, 176 Powders, 30-37 Power (of Microscope), 169-170 Pressure, 45-50, 51, 53, 54, 55, 57> 58, 62, 72 Effect on Thumb Mark of, 110-113 Guides to Estimating, 53, 54 Result of Oiled Cases on, 127 Priming, 30 Projection Lamp, 149 Proof Act, 15,...

Distortion In Photography

In view of the fact that photography must always play a most important role in the evidence of identification of firearms certain limitations which it possesses should be understood. The most important of these is Distortion. Probably every amateur has at some time or another taken a photograph of some relative or friend in a more or less recumbent position with the feet much nearer the camera than the head. The result is not usually flattering since in the photograph the feet may quite likely...

E

Ejection, 23-25, 108 Ejector Guns, 17 Mark, 108, 109, 117-119, 136 Eley, 68 Royal Small Arms Factory, 109 Engraving, Rifling, Degrees of, 142-144 Escapes, Gas, 54, 55, 84 Ex-centricity of Striker, 109, 114, 115 Expert, Home Office, 95, 104, 187, 190, 196 War Office, 104 Extraction, 23-25 Extractor Mark, 54, 108, 109,119,120,121,122, 123 Eye-piece, Goniometer, 199, 203, 204

Rifled Arms

All rifled arms fire a single projectile, or bullet while the purpose of the rifling, as is generally known, is to give the bullet a spin about its longitudinal axis during its passage along the bore. On leaving the muzzle of the weapon the bullet continues to spin, and this gyroscopic action maintains the bullet in stable nose-on flight during its passage through the air, which reduces air-resistance and adds enormously to the degree of accuracy obtainable, even at long ranges. Rifled arms...

Info

(3) Neither the police nor the public have a sufficient knowledge of firearms for the information, even if correct, to be of any real value. Let me try to explain these reasons at greater length. Bullets do not always bottom the grooves, and consequently it is then impossible to measure the depth of the groove by measurements of the engraving on the bullet. But in any case all measurements made with a micrometer eye-piece are difficult to make and require much skill and practice. The difference...

Of Firearms

THERE is one problem of identification which I have not as yet mentioned. On the discovery of a crime cartridge case, or the recovery of a crime bullet, the question may arise as to whether it is possible to ascertain the particular type and make of weapon with which the crime was committed. And since a crime bullet is probably recovered more frequently than a crime cartridge case I will try first to consider the problem as presented by a fired bullet. It has already been seen that rifling...

Unaccountable Marks

It sometimes happens that some very pronounced and seemingly distinctive mark is to be found on the base of a fired cartridge, and an inexperienced investigator will quite naturally think that he has here got an ideal thumb-mark. When he finds that this mark is not repeated on other cases which he has reason to suspect were fired from the same weapon he may easily be drawn to conclude that these other cartridges were actually fired by a different weapon. Accordingly it should be realised that...

Fired Cartridge Cases

The pressure developed in the upper cartridge was normal and the various marks arc clearly imprinted. In the lower cartridge the pressure was feeble, and the markings are much less strongly marked. But the two sets of markings will be seen to correspond been forced down so that it cannot engage with the rebound bent, with the result that the hammer can be pushed forwards without any check. And there is the further fact that since the sear tail was resting on the wood it would be lifted up still...

The Striker Indentation

The striker indentation can provide invaluable help in determining the thumb-mark of a weapon, although sometimes it is of little assistance. It has already been explained that strikers, or firing-pins, are individually different and that their noses are covered with markings. These markings often take the form of a number of small concentric rings, and for this reason when the imprints of such rings are found in the striker indentation of a fired cartridge great caution is necessary in...

Extraction And Ejection

After a cartridge has been fired the empty case must obviously be removed from the chamber before the weapon can be reloaded with another round. In the majority of modern firearms the mere fact of opening the breech after firing automatically ejects the fired case but in others the fired case is only partially unseated from its position in the chamber, and has to be removed by hand. This is the difference between ejection and extraction. And since the effects of both extraction and ejection on...

Cartridges And Their Components

MODERN cartridges differ greatly in outward appearance, but they are really all similar in that they consist of four main components the cartridge case the cap the powder, or propellant and the projectile, which may be either a single bullet or a charge of shot, when wads are also included. Cartridge Cases. The cartridge case, as its name infers, is the case which holds the other three components. Cases are made of brass, paper and brass, or copper, according to the type of weapon in which they...

Fatal Shot

Cal Rifle Powder Charge

WHEN a human being is found shot there are four possible alternatives for the cause of the tragedy accident, suicide, manslaughter, and murder. And before any very definite opinion can be formed certain problems must be considered in order to enable the authorities to formulate their conclusion. Probably one of the first of these problems will be the range of the fatal shot, that is the distance from which the shot was fired. It will, therefore, be but natural if we turn our attention to this...

Shot

In a shotgun cartridge the projectile consists principally of shot, although there are also some wads which ought to be included. Shot, as is generally known, consists of small lead balls, or pellets. These pellets are of different sizes, and these sizes are denoted by numbers. Shot is sometimes described as Drop or Soft shot and Chilled or Hard shot, but these names are really misleading. All shot, except the very largest sizes, is made by dropping molten lead from the top of a high tower into...

The Identification Of Firearms By Means Of Fired Bullets

SO far we have only considered the methods employed in the identification of individual firearms by means of fired cartridge cases. But it may easily happen that the only bit of material evidence available is the bullet which has been extracted from a victim, and in such circumstances the task of identification must be effected by marrying this bullet to a particular weapon. The general principle employed is exactly the same as that used with fired cartridge cases. No two barrels are...

Exactly

A and B are the caps of two different -303 cartridges, both fired by the same rifle. The right hand photograph is composite, the central portion of B being superimposed over the corresponding portion of A. The exact matching of all the striations on the two different caps caused by the imprint of the breech face of the bolt is convincing and obvious. There could be no possible doubt that both these cartridges must have been movement of the pin as well as longitudinal movement. While if the pin...

Testing Trigger Pulls

Forensic Ballistics Testing

It may frequendy happen that a test is necessary to determine the weight of the trigger pull of some weapon, and consequently a knowledge of the correct method of making such a test is essential. The commonest method is to use a trigger tester which is made in the form of a spring balance. Such testers are light, portable and convenient, and are consequently used largely by amateurs as well as by gunmakers. They serve their purpose well enough if an approximate reading is all that is required,...

The Effect Of Pressure

I have already mentioned in this chapter that the distinctness with which the thumb-mark of any breech face is imprinted on the base of a cartridge varies with the pressure. This is really obvious but the obvious seems to be forgotten so frequently that it is impossible to emphasise too strongly the great importance of pressure in firearm identification. It has already been explained in Chapter III that the higher the pressure the more the cap and base of the cartridge are flattened against the...

Smoothbores

At the present time most smooth-bores are used only for firing charges of small shot, and by far the greater majority in existence are ordinary shotguns, or sporting game guns, used for shooting small game. Shotguns are almost invariably made double-barrelled, the two barrels being placed side by side, although they are sometimes placed one over the other, when the gun is called an Over and Under' gun. Double-barrelled shotguns are made with outside hammers and with hammerless actions, in which...

Bullet Striations Comparison

The same two Bullets shown in Plate XXX, but as viewed with the A portion of the right-hand bullet appears in the right-hand half of the field, and a portion of the left-hand bullet in tbe left half. The striations on the two bullets match exactly nickel-jacketed bullets in Plate XXVI. In both cases the engraving consists of deep major furrows with fine striations in between these major furrows. On each fired bullet the deep furrows have been engraved by the lands, and the striations in between...

Accidental Discharge

Forensic Ballistics

One of the commonest causes of shooting fatalities is the accidental discharge of a weapon which was loaded and at full cock, and not a single shooting season passes without some such fatal accidents being reported. Anyone carrying a gun may stumble and drop his gun, when the blow which the latter receives on falling is liable to jar the lock or locks off, and thus cause an accidental discharge. The possibility of this happening is almost too well known to need emphasis, but it may not be out...

Identification Of Firearm Through Barrel Lands Grooves Twist

Two different 38 lead revolver bullets both fired bv the same revolver Tbc striations on these bullets are finer than those on the bullets shown in Plates XXX to XXXIII, and consequently a higher magnification has been employed which renders it only possible to show a portion of the bullets in the Plate is situated centrally in the field of view of the microscope. If it has been correctly attached to the holder and the spindle is revolved every part of the bullet can be examined in turn without...

Lands And Grooves Ballistics

Forensic Ballistics

And those portions of the bore which are situated between the grooves are known as lands. Gauge or Calibre- Both types of firearms are classified by the Gauge, or Calibre, of their bores that is by the internal dimension of the barrel A different system of measuring, however, exists for large smooth-bores and rifled arms. Large smooth-bores are measured by the number of Pig. x. Cross-section of a rifled barrel showing the grooves and lands. Pig. x. Cross-section of a rifled barrel showing the...

Metallic Fouling And Wear

Forensic Breach Face Marks

When a number of shots are fired through a rifle small portions of the outside of the bullet are frequendy removed during its passage down the bore and left adhering to the surface of the bore. At first only the smallest particles of the bullet strip, but these may become almost fused on to the inside of the barrel by the extreme heat generated, and are not easily removed. The uneven projections thus formed scrape the surface of each successive bullet and gradually increase in size until the...

Introduction

DURING the past few years it has so happened that I have been called as an expert witness or adviser in various legal cases in which firearms played an important part The experience which I have so gained has convinced me of the widespread ignorance of firearms which exists in quarters in which a correct understanding of the elementary principles of the subject would appear to be essential In fact, all too frequently this ignorance can be described only as' appalling. I feel, therefore, that...

Compared

When evidence of the identity of some particular arm can be established both by the evidence of a fired bullet and that of a fired cartridge case, the question may arise as to which is the more reliable. There can only be one answer both are equally reliable provided both can be put forward in a manner which can be appreciated and understood by a non-technical jury. This is the crux of the whole matter, for it is far more difficult to establish identity by means of a fired bullet than by means...

1

Effected the task of identifying these revolvers by means of ordinary microscopes and not by a comparison microscope. This shows what can be done by competent experts and emphasises the fact, which should be obvious, that it is not the instrument which effects the identification but the man who uses the instrument. The manner in which the work of identification was conducted and in which the evidence was prepared was a model of how such work should be carried out and such evidence should be...

The Identification Of Firearms By Means Of Fired Cartridge Cases

IN the great majority of cases of murder by shooting there is seldom much doubt as to the weapon which was used, but there are occasions when the definite identification of some particular firearm forges the final link in the chain of proof. In this country the most famous example of this type of evidence is the Gutteridge case, in which the facts were briefly as follows. In a motor-car which had undoubtedly been used by the murderers of P.C. Gutteridge the police found a fired revolver...

Photomicrography

As has already been stated any evidence of identification which is unsupported by photographs cannot be regarded as being anything more than an expression of opinion. Photographs are, accordingly, essential and such as are deemed necessary must be taken through the microscope. Once again it must be emphasised that no higher power than is absolutely necessary to show the detail should ever be used. And in the case of photographs which are to be handed to a non-technical jury this rule is more...

X X

So let us now turn to a consideration of the principles governing the task of establishing the identity of a particular weapon by means of the secondary markings on fired bullets. These secondary markings consist of a number of parallel striations in the furrows cut by the lands, and also in between these land furrows. These striations are all caused by minute tool, or other marks on the surface of the bore which scratch the outside surface of the bullet as it passes along the bore. In fact,...

Potassium Chloride Semi Auto Pistol

Of humidity in different places and in the same place with different weather. The products of combustion, however, can hasten or retard the effects of the humidity of the air. For example, the most potent factor in hastening rusting is one of the products of combustion of the cap composition, and not of the powder, as is popularly supposed. Some types of caps are primed with a composition which contains potassium chlorate. On the cap being fired this substance gives up its oxygen very readily...

R

Range, Blackening, 58, 59 Scorching, 57, 58 Unburnt Powder Grain, 59-67, 68, 69, 70 Rebound Bent, 93, 95 Revolvers, Double Action, 21,99,102,103 Single Action, 21,99 Revolving Stage, 128,174 Rifle Powders see Powders Rifled Arm, Definition of, 13 Arms, Types of, 19-24 Rifles, Military, 20 Rifling, Pitch of, How Measured, 199, 203,204 Types of, 140,141 Rules, Proof, 15 Rust, 81, 82, 83, 84

The Left Lock of the same

The sear tail hangs below the bottom of the lock plate see arrow and rested on the wood of the stock, thus rendering the gun highly dangerous and peculiarly liable to accidental discharge But as in scorching the range is really so close that for all practical purposes these niceties may be ignored, although it is as well that they should be understood. Blackening with a high-power rifle, such as a service rifle, can occur up to about 9 inches and with a revolver or pistol up to about 6 inches....

Forensic Microscope with the Comparison Eyepiece in position

The bullets can be seen on their holders, and the two projeccion lamps are attached to the fronts focussed with the microscope. Any markings along that part of the edge will then be seen distinctly. The case is then rotated so that every part of the side can be examined in turn. I have purposely explained the procedure of examination with some detail because the instrument usually adopted and recommended for this work is that known as a Comparison Microscope. Such an instrument really consists...

Powders

Ballistic Forensic Cases

Any firearm is really a machine for controlling the application of force which propels the bullet, or shot charge, through the air. The force necessary for this propulsion is generated by the very rapid production of gases resulting from the combustion of the powder charge and on this account all powders which are used in firearms are termed propellants i, rim-fire Long Rifle 2, -300 Rook Rifle, straight and rimmed case 3, 303 Mark VII, bottle-necked rimmed case and pointed bullet 4, -303 Mark...

Unfired and Fired Bullets

A is an unfired lead 3ik gt revolver bullet. B is a similar bullet which has been fired by a Webley revolver. The Webley typo of rifling 7 grooves, right-hand twist, narrow lands is distinctly engraved on the bullet. The arrow indicates the skid mark. C is an unfired nickel-jacketed 7 63 mm. pistol bullet. And D is a similar bullet fired by a Schwartloze self-loading pistol. The engraving is that of the type oi rifling commonly used in the early models of self-loading pistols 4 grooves, right...

Four Fired Bullets showing different types of Rifling Engraving

On the left is a -380 lead revolver bullet with the Smith and Wesson type of engraving 5 grooves, right-hand twist, lands and grooves of equal width . Next is a 0 mm. nickel-jacketed bullet fired froin an Astra self-loading pistol. This bullet fitted the bore tightly and is engraved all round its circumference, the striations made by the grooves being clearly visible between the deep land furrows. The rifling is the Browning type 6 grooves, right-hand twist, narrow lands and wide grooves . Next...

Major Sir Gerald Burrard

Self-Loading Pistol and the Base of Cartridge which was fired from this pistol The marks on the breech face have been imprinted on the base of the cartridge, and in order to simplify the identification of the different marks and their corresponding imprints they have all been numbered. The following marks arc indicated on the breech face i, a deep indentation possibly caused by an accidental blow with the end of a cleaning rod 2, irregular roughening 3, a large...

Other Problems

A problem with which those investigating a crime are frequently confronted is to determine the time which has probably elapsed since the firing of a shot. A weapon may be discovered which may, or may not, have been used by the criminal. The barrel is clearly fouled and so the question arises, is it possible by an examination of the barrel to ascertain with any degree of accuracy the period of time which has elapsed since that weapon was fired Before making any attempt to answer this question it...