Some Actual Examples

The whole science of identifying individual weapons by means of microscopic examinations of fired bullets and fired cartridge cases has probably been studied in America longer than in any other country, and its investigation on scientific lines was really due to the appalling blunders of the prosecution in a particular murder charge. In Army Ordnance of July-August, 1933, Major J. S. Hatcher stated that the present science of firearms identification in America really owes its inception to the...

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

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...

Info

Forensic Breech Block Markings

I will give more details of this case later and merely mention now that it has never been generally realised that this work of identification was carried out by the War Office, and not by any Home Office or Police experts so it is but fair that honour should be given where it is due. The only other case which has been heard in England in which this type of evidence was used as the vital issue was the case of the shot Cypriot doctor, which was heard in March, 1933. I will also allude to this...

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

M16 Barrel Rifling Pictures

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...

C

Ballistic Forensic Cases

Cartridge Case B A 6-35 mm. Cartridge Case which was fired in a Pistol with rather a loose chamber Not the expansion of the forward part of tlx- ease. The longitudinal scratch should also be noted C A 6-35 mm. Cartridge which was fired in another Pistol The chamber was tighter and there is less expansion of the case. But there is a longitudinal scratch very similar to that in the case shown in the middle photograph means instantaneous, and is slow compared to the...

The Case Of The Shot Cypriot Doctor

The only other occasion on which evidence of firearms identification has been put forward in England in a murder trial as a major issue was in March, 1933, and this case may be of interest as expert evidence was brought forward both by the prosecution and the defence.1 The facts leading up to the trial were briefly as follows. A man named Zemenides, who styled himself as Doctor, was the apparent head of the Cypriot community in London. He had, not to put too fine a point on it, swindled 1 At...

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...

Marks On The Sides Of Hred Cases

So far we have only considered the marks on the base of a fired cartridge case. But there are sometimes marks on the side of a case which, if not so important as those on the base, can be of help in the task of identifying an arm. So it is essential that their usefulness and their limitations should be appreciated. These marks can really be classified under two main headings Extractor Marks, and Scrapes. Extractor Marks are of two entirely distinct types. The first type is produced by the claw...

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...