Manufacturing of firearms parts: relevant sources of information and contribution in a forensic context

In the context of forensic cases involving firearms, a major issue to address is the identification of the firearm used to discharge questioned elements of ammunition – bullets or cartridge cases – found during the scene investigation. When a questioned firearm is available, reference bullets and cartridge cases are produced through controlled test-fires. The marks left on both the questioned and reference elements of ammunition are analysed before being compared. The processes used to manufacture the firearms tend to influence the type and frequency of some of these marks. Knowing how the questioned firearm was produced is a key element to identify the relevant marks for comparison purposes. Finding this information can be challenging, as it is not necessarily publicly available. After presenting the manufacturing processes used to produce the main parts of firearms in contact with the elements of ammunition, this review includes an updated list of processes used by specific manufacturers, relying not only on the literature. The results highlight the necessity to consider a wide range of sources when gathering information about the manufacturing processes. Apart from general and specialized forensic literature, the online content made available by the manufacturers themselves is also a valuable complementary source of information. Contacting the manufacturers or visiting their premises is sometimes necessary to understand the full extent of the processes and how they can influence the marks of forensic interest

Investigating the availability of 3D-printed firearm designs on the clear web.

The release of the plans of the 3D-printed Liberator firearm sparked a wave of new designs from creators worldwide, resulting in an extensive collection of 3D-printed firearm plans, in particular blueprints, and parts available for almost unrestricted download on the internet. Identifying and categorizing the diverse range of 3D-printed firearms and components pose a challenge due to the abundance of designs available. Between 2021 and April 2023, data was collected on over 2,100 3D-printed firearm plans. While blueprints of fully 3D-printed firearms initially dominated the scene, hybrid designs and parts kit completions / conversions (PKC) have gained popularity for their improved reliability and performance. The now highly networked community offers considerable support with detailed instructions and procedures, providing precise guidance for construction. This systematic classification, grouping and structuration of the recorded data on the Clear Web supported the identification of patterns of the main threat trends related to 3D-printed firearms

Comparison of three bullet recovery systems

Comparing the marks left on questioned bullets to those left on reference bullets is the main aim of a firearm identification expertise. Thus, producing reference bullets with a questioned firearm is an essential step. Different kinds of system have been developed to safely recover bullets fired from questioned firearms. However, the performance of each system and its impact on traces left on the bullets have not been addressed. Three bullet recovery systems – a horizontal water tank, a cotton tube and a recently designed fleece – were used to fire seven types of ammunition of various type, shape and casing. The bullets were then described and images of their surface were acquired with an automatic system to study the impact of each system on the bullets. The water tank is the more efficient system in terms of quality of the marks. However, it cannot be used to fire every type of ammunition. Some of them, such those used by law enforcement, tend to be damaged with this system. A way to mitigate the problem is to use the cotton or the fleece-based systems, the latter being more universal. It requires a cleaning step to remove all the fibres from the surface of the bullet, but the marks left by the weapon are still of interest

Cleaning deteriorated elements of ammunition: Development of a procedure applied to cartridge cases from the Second World War.

Deteriorated elements of ammunition can be found while investigating different types of events. Exposure to adverse environmental conditions may lead to metal alteration (corrosion) or organic material deposition (contaminations) on the exposed elements of ammunition. From a forensic perspective, both types of deterioration pose challenges when observing marks left by the firearms used to discharge the corresponding ammunition (e.g. firing pin, extractor). The longer the time of exposure to the adverse environmental conditions, the more challenging the observation of such marks. A literature review highlighted three previously published restorative methods used to clean deteriorated elements of ammunition. The aim of this research is to develop a cleaning procedure applicable to cartridge cases exposed to adverse environmental conditions, while avoiding the degradation of marks left by the firearms used to discharge the corresponding ammunition. A first batch of 21 brass cartridge cases dating back to the Second World War (WWII) was used to develop a cleaning sequence involving the three methods. The efficiency of each restorative method was qualitatively assessed using optical macroscopy and the Evofinder® ballistic identification system. The developed sequence relies on successive applications of Tickopur® TR 7 (a diluted soft metal cleaner), sulfuric acid and finally Aqua Regia (HCl 37% and HNO <sub>3</sub> 75%), all of them involving ultrasonic baths. The resulting cleaning sequence was subsequently applied to three batches of Second World War cartridge cases discovered in France and Russia. This sequential procedure allows the effective cleaning of WWII brass cartridge cases while highlighting different marks left by firing pins, extractors, ejectors, and breech faces. Applying a forensic analysis and comparison process to the marks highlighted on these elements of ammunition can support the verification of historical facts when reconstructing events which took place more than seventy years ago

How to recognize the traces left on a crime scene by a 3D-printed Liberator?: Part 1. Discharge, exterior ballistic and wounding potential

The Liberator is a firearm that can be manufactured from its blueprints, using a 3D-printer. This weapon made of nineteen pieces – eighteen in printed plastic and one metallic nail – raises questions such as its ability to fire a round, its wounding potential and the traces produced by its discharge. In particular, knowledge must be gained to infer that a 3D-printed handgun was used, reconstruct the shooting event involving such handgun, and gather information related to the type of 3D-printed handgun used. This study focused on the traces that could orientate forensic investigations when the use of a 3D-printed Liberator is suspected. In a first step, the Liberator was investigated to study its behaviour during the discharge and characterize traces produced by the discharge. To fulfil this goal, some Liberators were printed and assembled. Six Liberators fired a round. The discharge of the weapons was done under specific conditions allowing to collect ballistics data and traces produced by the shooting. The results showed that the barrel tended to break between the ignition of the primer and the moment the projectile exited the muzzle. The speed of the projectiles reached 140 m/s when the barrel broke, while it was about 170 m/s when barrel remained intact. The trajectory of the projectiles was sometimes disrupted, and the projectile tumbled on itself. It was thus very difficult to characterize the trajectory. The cavity wound caused by the fastest bullet was typical of a handgun wound firing a FMJ projectile (penetration of 21 cm in ballistics soap). On the other hand, the cavity caused by the slowest bullet was more representative of a splinter wound (penetration of 14 cm in ballistics soap). The study of gunshot residues collected on adhesive targets showed the presence of unburnt particles and small perforations caused by polymer pieces that concentrated around the entry holes

Recherches actuelles des géographes bâlois. A propos de l'atlas du nord-ouest de la Suisse, du sud de l'Alsace et du sud de la Forêt-Noire

Gallusser Werner A. Recherches actuelles des géographes bâlois. A propos de l'atlas du nord-ouest de la Suisse, du sud de l'Alsace et du sud de la Forêt-Noire . In: Revue Géographique de l'Est, tome 6, n°3-4, Juillet-décembre 1966. pp. 387-389

L'organisation suisse des routes nationales comme innovation de l'espace culturel

Abstract. — The present development of the Swiss national road network, composed of 6 and 4 lane motorways, as well as of 2 lane semi-motorways, is being carried out in sections throughout the Confederation. This is bringing about important modifications to the urban and rural areas which the searchers of the Geographical Institutions of Basle, Berne and Saint-Gall are attempting to discover.Gallusser Werner A. L'organisation suisse des routes nationales comme innovation de l'espace culturel. In: Revue Géographique de l'Est, tome 13, n°3, Juillet-septembre 1973. Transports et région : mémoires et notes. pp. 289-299

Recherches actuelles des géographes bâlois. A propos de l'atlas du nord-ouest de la Suisse, du sud de l'Alsace et du sud de la Forêt-Noire

Gallusser Werner A. Recherches actuelles des géographes bâlois. A propos de l'atlas du nord-ouest de la Suisse, du sud de l'Alsace et du sud de la Forêt-Noire . In: Revue Géographique de l'Est, tome 6, n°3-4, Juillet-décembre 1966. pp. 387-389