Forensic Ballistics in Court – Interpretation and Presentation of Firearms Evidence

About the Author xiii
<p>Introduction xv</p>
<p>About the companion website xix</p>
<p>1.0 Firearms History 1</p>
<p>1.0.1 Introduction 1</p>
<p>1.0.2 The flintlock 1</p>
<p>1.0.3 The percussion system 3</p>
<p>1.0.4 The pinfire system 3</p>
<p>1.0.5 The rimfire system 4</p>
<p>1.0.6 The Dreyse needle fire system 4</p>
<p>1.0.7 The centre fire system 5</p>
<p>1.0.8 The revolver 5</p>
<p>1.0.9 The self–loading pistol 6</p>
<p>Further reading 8</p>
<p>2.0 Weapon Types and Their Operation 9</p>
<p>2.0.1 Introduction 9</p>
<p>2.0.2 Handguns 9</p>
<p>2.0.3 Rifles 13</p>
<p>2.0.4 Shotguns 14</p>
<p>2.0.5 Combination weapons 15</p>
<p>2.0.6 Sub–machine guns 15</p>
<p>2.0.7 Assault rifles 16</p>
<p>2.0.8 Machine guns and heavy machine guns 16</p>
<p>2.0.9 Muzzle attachments 16</p>
<p>2.0.10 Important parts of a weapons mechanism 19</p>
<p>2.0.11 Bent and sear 20</p>
<p>2.0.12 Other important parts of a revolver mechanism 22</p>
<p>2.0.13 Hand and ratchet 23</p>
<p>Further reading 24</p>
<p>2.1 Gas and Air Powered Weapons 25</p>
<p>2.1.1 Introduction 25</p>
<p>2.1.2 Weapon types 25</p>
<p>2.1.3 Ammunition 28</p>
<p>2.1.4 Considerations 30</p>
<p>Further reading 31</p>
<p>2.2 Rifling Types and Their Identification 33</p>
<p>2.2.1 Introduction 33</p>
<p>2.2.2 Basics 34</p>
<p>2.2.3 Class characteristics 37</p>
<p>2.2.4 General introduction to rifling 38</p>
<p>Additional reading 42</p>
<p>2.3 Home–made, Improvised and Converted Firearms 43</p>
<p>2.3.1 Introduction 43</p>
<p>2.3.2 Improvised firearms 43</p>
<p>2.3.3 Converting air weapons 44</p>
<p>2.3.4 Home–made and converted toys and replica weapons 45</p>
<p>2.3.5 Home–made ammunition 48</p>
<p>Further reading 50</p>
<p>2.4 Antique Weapons 51</p>
<p>2.4.1 Introduction 51</p>
<p>2.4.2 Background 51</p>
<p>2.4.3 Defining antique 52</p>
<p>3.0 Proof Marks 55</p>
<p>3.0.1 Introduction 55</p>
<p>3.0.2 Proof marks 55</p>
<p>3.0.3 Types of proof 56</p>
<p>3.0.4 Proof marks and the examiner 56</p>
<p>3.0.5 Examples of proof marks 56</p>
<p>Further reading 61</p>
<p>4.0 A Brief History of Ammunition 63</p>
<p>4.0.1 Introduction 63</p>
<p>4.0.2 Basics 63</p>
<p>Further reading 66</p>
<p>4.1 Ammunition Components 67</p>
<p>4.1.1 Introduction 67</p>
<p>4.1.2 Basics 67</p>
<p>4.1.3 Ammunition types 68</p>
<p>4.1.4 Primer cap types 69</p>
<p>4.1.5 Cartridge cases 70</p>
<p>4.1.6 Shotgun ammunition 73</p>
<p>Further reading 79</p>
<p>4.2 Bullet Types 81</p>
<p>4.2.1 Introduction 81</p>
<p>4.2.2 Basics 81</p>
<p>4.2.3 Bullet materials 81</p>
<p>4.2.4 Other bullet types 83</p>
<p>4.2.5 Bullet nose configuration 83</p>
<p>4.2.6 Bullet base configuration 85</p>
<p>4.2.7 Bullet lubrication 85</p>
<p>Further reading 86</p>
<p>4.3 Headstamps and Other Identifying Features on Ammunition 87</p>
<p>4.3.1 Introduction 87</p>
<p>4.3.2 Basics 88</p>
<p>4.3.3 Clandestine ammunition 89</p>
<p>4.3.4 Colour coding of ammunition 90</p>
<p>Further reading 91</p>
<p>4.4 Non–toxic and Frangible Bullets 93</p>
<p>4.4.1 Introduction 93</p>
<p>4.4.2 Elimination of lead in ammunition 93</p>
<p>4.4.3 Materials used in non–toxic ammunition 94</p>
<p>4.4.4 The current situation 94</p>
<p>Further reading 96</p>
<p>4.5 Non–toxic Shot 97</p>
<p>4.5.1 Introduction 97</p>
<p>4.5.2 Materials used in non–toxic shotgun ammunition 97</p>
<p>Suggested further reading 100</p>
<p>4.6 A Brief History of Propellants 101</p>
<p>4.6.1 Introduction 101</p>
<p>4.6.2 Basics 101</p>
<p>4.6.3 Black powder 102</p>
<p>4.6.4 Nitro propellants 104</p>
<p>4.6.5 Dating of ammunition 107</p>
<p>4.6.6 Reduced loads for target shooting 107</p>
<p>Further reading 108</p>
<p>4.7 Priming Compounds 109</p>
<p>4.7.1 Introduction 109</p>
<p>4.7.2 Basics 110</p>
<p>4.7.3 A short history of priming compounds 110</p>
<p>4.7.4 Manufacture 113</p>
<p>4.7.5 Accidental discharge of primers 113</p>
<p>Further reading 114</p>
<p>5.0 An Introduction to Ballistics 115</p>
<p>5.0.1 Introduction 115</p>
<p>5.0.2 Basics 115</p>
<p>5.0.3 Background 115</p>
<p>Further reading 116</p>
<p>5.1 Internal Ballistics 117</p>
<p>5.1.1 Introduction 117</p>
<p>5.1.2 Basics 117</p>
<p>5.1.3 Recoil 118</p>
<p>5.1.4 Barrel pressure 120</p>
<p>Further reading 121</p>
<p>5.2 External Ballistics 123</p>
<p>5.2.1 Introduction 123</p>
<p>5.2.2 Basics 124</p>
<p>5.2.3 Maximum range of missiles 126</p>
<p>5.2.4 Maximum altitude that a bullet will attain 130</p>
<p>5.2.5 Terminal velocity 131</p>
<p>5.2.6 Use of sight to compensate for bullet drop 132</p>
<p>5.2.7 Other influencing factors 132</p>
<p>5.2.8 Muzzle energy 134</p>
<p>5.2.9 Momentum 135</p>
<p>Further reading 135</p>
<p>5.3 Terminal Ballistics 137</p>
<p>5.3.1 Introduction 137</p>
<p>5.3.2 Basics 137</p>
<p>5.3.3 General wound ballistic concepts 139</p>
<p>5.3.4 Other factors influencing the wounding capabilities of a missile 144</p>
<p>5.3.5 Bullet performance and wounding capabilities 145</p>
<p>5.3.6 Relative stopping power (RSP) 147</p>
<p>5.3.7 Bullet resistant vests (BRV) 149</p>
<p>Further reading 152</p>
<p>6.0 A Brief History of Forensic Firearms Identification 153</p>
<p>6.0.1 Introduction 153</p>
<p>6.0.2 Early cases involving bullet identification 154</p>
<p>6.0.3 Use of photomicrographs 154</p>
<p>6.0.4 Identification of weapon from breech face markings 155</p>
<p>6.0.5 Early use of comparison microscope 155</p>
<p>6.0.6 Introduction of the binocular comparison microscope 156</p>
<p>6.0.7 Improvements in illumination 157</p>
<p>6.0.8 Photography of stria 157</p>
<p>6.0.9 Modern technology for stria comparison 157</p>
<p>Suggested further reading 160</p>
<p>7.0 Basic Concepts of Striation Matching 161</p>
<p>7.0.1 Introduction 161</p>
<p>7.0.2 Basics 162</p>
<p>7.0.3 Identification of weapon type 164</p>
<p>7.0.4 Individual characteristics on cartridge cases 165</p>
<p>7.0.5 Formation of stria 166</p>
<p>7.0.6 Problematical areas 167</p>
<p>Further reading 172</p>
<p>7.1 Basic Concepts in Comparison Microscopy 173</p>
<p>7.1.1 Introduction 173</p>
<p>7.1.2 Basic methodology and background to stria comparisons 174</p>
<p>7.1.3 Lighting used for comparison microscopy 175</p>
<p>7.1.4 The concept of consecutive matching stria 177</p>
<p>7.1.5 Obtaining control samples 177</p>
<p>7.1.6 Manufacturing marks on ammunition 178</p>
<p>7.1.7 Recovery methods for fired bullets 178</p>
<p>7.1.8 Conclusion 180</p>
<p>Further reading 181</p>
<p>7.2 The Concept of Consecutive Matching Stria 183</p>
<p>7.2.1 Introduction 183</p>
<p>7.2.2 Basics 183</p>
<p>7.2.3 Arguments for and against the concept of stria comparisons 186</p>
<p>Further reading 187</p>
<p>7.3 A Statistical Model to Illustrate the Concept of Individuality in Striation Matches 189</p>
<p>7.3.1 Introduction 189</p>
<p>7.3.2 Basics 189</p>
<p>7.3.3 Stria individuality 190</p>
<p>7.3.4 Philosophy 191</p>
<p>References 193</p>
<p>8.0 Accidental Discharge 195</p>
<p>8.0.1 Introduction 195</p>
<p>8.0.2 Basics 197</p>
<p>8.0.3 Trigger mechanisms 197</p>
<p>8.0.4 Reasons for an accidental discharge 198</p>
<p>8.0.5 Negligent discharges 203</p>
<p>Further reading 204</p>
<p>9.0 Identification of Calibre from the Bullet Entry Hole 205</p>
<p>9.0.1 Introduction 205</p>
<p>9.0.2 Basics 206</p>
<p>9.0.3 Determination of bullet type 207</p>
<p>Further reading 208</p>
<p>10.0 Ricochet Analysis 209</p>
<p>10.0.1 Introduction 209</p>
<p>10.0.2 Basics 209</p>
<p>10.0.3 Variables influencing the liability of a missile to ricochet 210</p>
<p>Further reading 213</p>
<p>11.0 Bullet Penetration and Trajectory through Glass 215</p>
<p>11.0.1 Introduction 215</p>
<p>11.0.2 Glass types and glass substitutes 215</p>
<p>11.0.3 Deviation of missile after penetrating glass 217</p>
<p>11.0.4 Penetration of normal window glass 217</p>
<p>11.0.5 Penetration of laminated and bullet–resistant glass 218</p>
<p>11.0.6 Penetration of tempered or toughened glass 219</p>
<p>11.0.7 Determination of bullet type from the entry hole 220</p>
<p>11.0.8 Deflection of bullet by glass 221</p>
<p>Further reading and references 223</p>
<p>12.0 Range of Firing Estimations and Bullet Hole Examinations 225</p>
<p>12.0.1 Introduction 225</p>
<p>12.0.2 Basics 225</p>
<p>12.0.3 Range of firing estimations for pistols and rifles 227</p>
<p>12.0.4 Extended range of fire estimations 230</p>
<p>12.0.5 Range of firing estimations on badly decomposed bodies 231</p>
<p>12.0.6 Bullet wipe marks 231</p>
<p>12.1 Chemical Tests for Range of Fire Estimations and Bullet Entry/Exit Hole Identification 235</p>
<p>12.1.1 Introduction 235</p>
<p>12.1.2 Chemical tests for range of firing estimations 235</p>
<p>12.1.3 Range of firing estimations on heavily bloodstained garments 237</p>
<p>12.1.4 Range of firing estimations for non–toxic non–lead primers 238</p>
<p>Further reading 239</p>
<p>12.2 Range of Fire Estimations for Shotguns 241</p>
<p>12.2.1 Introduction 241</p>
<p>12.2.2 Basics 242</p>
<p>12.2.3 Shotgun cartridges fired in revolvers 246</p>
<p>Suggested further reading 247</p>
<p>13.0 The Use of X–ray Photography for Projectile Identification 249</p>
<p>13.0.1 Introduction 249</p>
<p>13.0.2 Estimation of calibre from X–ray photographs 250</p>
<p>Further reading 254</p>
<p>14.0 Gunshot Residue Examination 255</p>
<p>14.0.1 Introduction 255</p>
<p>14.0.2 Basics 256</p>
<p>14.0.3 Identification of GSR Particles 257</p>
<p>14.0.4 The use of the scanning electron microscope (SEM) with energy dispersive X–Ray analysis (EDX) for the detection and analysis of GSR particles 259</p>
<p>14.0.5 Sample collection 260</p>
<p>14.0.6 GSR retention 263</p>
<p>14.0.7 Interpretation of results 264</p>
<p>14.0.8 Identification of type of ammunition and country or origin from GSR composition 265</p>
<p>14.0.9 Environmental contaminants 267</p>
<p>14.0.10 Extending the period over which GSR particles can be recovered 269</p>
<p>14.0.11 General considerations to be made when examining GSR analysis results 272</p>
<p>14.0.12 Discussion 274</p>
<p>References 275</p>
<p>15.0 Gun Handling Tests 277</p>
<p>15.0.1 Introduction 277</p>
<p>15.0.2 History 278</p>
<p>15.0.3 Methodology for the use of Ferrozine 279</p>
<p>Further reading 283</p>
<p>16.0 Laser–etched Serial Numbers and Bar Codes 285</p>
<p>16.0.1 Introduction 285</p>
<p>16.0.2 Laser–etched serial numbers 285</p>
<p>16.0.3 Bar codes 286</p>
<p>16.0.4 Conclusion 287</p>
<p>Further reading 287</p>
<p>17.0 Classification of Firearms–related Death 289</p>
<p>17.0.1 Introduction 289</p>
<p>17.0.2 Basics 289</p>
<p>17.0.3 Multiple shot suicides 290</p>
<p>References and further reading 293</p>
<p>18.0 Practical Considerations in a Firearms Case from a Legal Point of View 295</p>
<p>18.0.1 Introduction 295</p>
<p>18.0.2 Key questions 296</p>
<p>18.0.3 Legal challenges to forensic firearms evidence in the USA 298</p>
<p>18.0.4 Conclusion 300</p>
<p>Further reading and references 300</p>
<p>19.0 Qualifying the Expert and Cross–examination Questions 301</p>
<p>19.0.1 Definition 301</p>
<p>19.0.2 Introduction 301</p>
<p>19.0.3 Qualifying the expert 302</p>
<p>19.0.4 General background questions 303</p>
<p>19.0.5 Comparison microscopy 303</p>
<p>19.0.6 Gunshot residue 306</p>
<p>19.0.7 Ferrozine test 308</p>
<p>Further reading 308</p>
<p>20.0 Chain of Custody 309</p>
<p>20.0.1 Introduction 309</p>
<p>20.0.2 Basics 309</p>
<p>20.0.3 Process 310</p>
<p>20.0.4 In court 310</p>
<p>Further reading 311</p>
<p>Appendix 1 Standard of Review: Daubert Trilogy 313</p>
<p>Appendix 2 Commercial and General Abbreviations for Bullet Configurations 317</p>
<p>Appendix 3 Some of the More Common Trade Names 323</p>
<p>Appendix 4 Important dates in the History of Firearms from 1247 335</p>
<p>Appendix 5 Dates for the Introduction of Various Cartridges by Calibre 341</p>
<p>Appendix 6 Some Trademarks Found on Guns 345</p>
<p>Appendix 7 General Firearms Values Conversion Table 349</p>
<p>Appendix 8 Hearing Loss 351</p>
<p>Appendix 9 A List of Handgun Cartridges 355</p>
<p>Appendix 10 A List of Rifle Cartridges 357</p>
<p>Appendix 11 Air Weapon Legislation 361</p>
<p>Index 367</p>