Forensic ballistics.

 

Forensic ballistics is a system of rules and recommendations (knowledge system) for detection, fixation, preservation, seizure and testing of firearms, ammunition and traces of weapons and ammunition. These are also the typical evidence that is being produced in committing a firearm offense. It occupies a very important place in forensic science. The object of judicial ballistics is: - to reveal the specifics of the processes and phenomena of the shot, - to reveal the regularities of the formation of traces and other material evidence, - to investigate the species and their significance for the investigation - the development of means and means, rules and recommendations for the detection, preservation, fixing, seizure and investigation of weapons and ammunition and their traces. firearms carried out with a firearm, as:

helps to clarify a wide range of circumstances about the location and timing of the shot, the direction of the bullet, the suitability of the self-made weapon, etc., - insures specialized inspection of the site of search, search and seizure, and personal search in cases of use of firearms ; - it is possible to identify the weapon on the found cartridges and bullets by performing a forensic-ballistic expertise and, where this is not possible, to determine its group membership. When shooting with a firearm, there are simultaneously several major processes that are important for the formation of traces and other material evidence. The first is the thermal process. When the process is fully developed, the temperature of the shot reaches 3000 ° C. This is of immediate importance for the formation of the traces. The second process is the pressure process. It is the result of the gas discharge when the gunpowder is burned and from 250-360 in the beginning the pressure can reach 3500 atmospheres. Simultaneously with the thermal process and the pressure there are also chemical, physical and mechanical processes. They are also important for the formation of the traces and especially for the emergence of the so-called secondary traces. Two major types of traces are formed from the shot, they follow the reflections (traces in the narrow sense of the word) and other traces (in the broad sense of the word ). The first group of traces allows the weapon to be identified and, when this is impossible, to identify the group's affiliation; the second - to clarify other circumstances in the case. Traces of reflections are formed on the bullets and shells. The bullet traces are formed by the barrel grooves of the barrel, reflecting their direction, width, depth and other peculiarities; on the shell - when charging, firing and separating the cartridge. Traces on the bullet and the cartridge can identify the weapon because they possess sufficient private identification signs as a result of the mechanism of their formation under the influence of heat and other shots, atmospheric pressure, etc. The traces in the broad sense of the word are three types: secondary (additional); trace the bullet to one or more objects on the scene and trace it to the human body (the blind channels have an inlet hole as a result of the mucosal reaction of the body and trace breaks with inlet and outlet). The secondary (additional) traces have the greatest legal significance. Depending on the origin, the secondary traces are: - the mechanical action of the gun gases. They are encountered with a shot of 5-10 cm and depend on three factors: the quantity and quality of gunpowder, the combustion intensity and the nature of the barrier. They can cause tears in the place of the inlet, - they are monitored by the thermal action of the gun gases - burns, burns, fires. They are shot at a close shot and depend on the gunpowder, the barrel length and the character of the barrier; particles of soot, rays, and weapon oil. metallisation belt and pollution; - smoking-watching. They are formed in both types of gunpowder and are arranged radially in two parts - central and peripheral. Like the other traces, they give valuable information about the distance from which the shot was made, - Watch out of unburnt gunpowder, - Watch out of weapon oil (usually after the first shot). - metallic dusts. The secondary traces are formed only under certain conditions - a small distance between the post-forming and the post-reception object and the normal course of the shots. In addition, these traces are subject to rapid and irreversible alterations under the influence of external factors. The secondary traces are important for the investigation in three directions: - to determine the distance from which the shot was made - to determine the time of the shot - to determine the group membership of the weapon and whether they are trapped by the first or subsequent shots. Discovery of the weapon and ammunition, except for the needs of the expert, also counts for establishing the crime scene, for clarity