Comparing Bullets скачать в хорошем качестве

Comparing Bullets

Comparing Bullets Comparison Microscope A comparison microscope is a device used to analyze side-by-side specimens. It consists of two microscopes connected by an optical bridge, which results in a split view window enabling two separate objects to be viewed simultaneously. This avoids the observer having to rely on memory when comparing two objects under a conventional microscope. Bolt‐Face Signatures Firing pin impressions and breech block markings on the primer (also called bolt‐face signatures) should be compared first because they can only be produced by firing a cartridge in a firearm. Chambering, extractor, ejector, and magazine marks may be made by loading a cartridge in a weapon without firing it. Developing a Comparison Test‐fired bullets are fired through the firearm The resulting bullets are then compared with each other to verify consistency of marks with the firearms barrel. Making a Match If a distinctive pattern of parallel striations are found on the test bullets then a technician can rotate the evidence bullet slowly in an attempt to find a matching pattern. Slippage Marks Slippage marks are made on a bullet when it slips along the tops of the lands instead of being firmly gripped by the rifling. They are the result of the barrel being worn or having been bored out and may also result if a sub‐caliber bullet is fired in a weapon. *Slippage marks are hard to replicate in test firings. Categorizing Findings Positive identification – The class characteristics are consistent and individual characteristics match. This means that the likelihood that a firearm other than the firearm submitted for examination fired the questioned bullet or cartridge is very unlikely. Negative identification - The questioned bullet or cartridge was not fired in the submitted weapon. The class characteristics did not match. Inconclusive - There was too little information on which to base a conclusion or that while the class characteristics matched, sufficient individual characteristics to declare a match could not be found. Link to Lecture Slides: https://drive.google.com/file/d/1hvyW... *Due to the description character limit the full work cited for "Comparing Bullets" can be viewed at... https://drive.google.com/file/d/1Wmfq...