What is ballistics 1 Introduction Ballistic evidence helps

What is ballistics? 1

Introduction Ballistic evidence helps explain: What type of firearm was used. The caliber of the bullet. The number of bullets fired. Position of shooter. Whether a weapon was fired recently. If a firearm was used in previous crimes. Forensic Science: Fundamentals & Investigations, Chapter 17 2

Firearm Nomenclature Barrel Muzzle Extractor Trigger Hammer Safety Chamber

Ammunition bsapp. com

Bullets, Cartridges, and Calibers Bullet->projectile Cartridge->holds bullet and GP Case, shell, casing>remains when bullet it fired Caliber->diameter of cartridge (bullet). 5

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Three Main Shapes bsapp. com

Round Nose Maximum penetration Cheapest to manufacture Easily loads into chambers bsapp. com

Hollow Point Spreads on impact Causes additional damage to target Inhibits penetration bsapp. com

Wad Cutter Used exclusively as a practice load Minimizes penetration Rips a hole in target paper which is visible by the shooter bsapp. com

Three Basic Compositions of Bullets Lead ½ Jacketed (Full metal jacket) bsapp. com

Lead Cheap Dense Soft Easy to mold bsapp. com

½ Jacketed A lead bullet coated with copper half way up the exposed portion of the bullet Used primarily for hollow points Copper improves exit velocity Lead promotes mushrooming bsapp. com

Jacketed A lead bullet completely coated in copper Copper improves exit velocity Used to hold the shape of the bullet in an effort to maximize penetration bsapp. com

Caliber of the Cartridge Caliber is a measure the diameter of the cartridge in hundredths of an inch. Common calibers include. 22, . 25, . 357, . 38, . 44, and. 45. Why should the caliber of ammunition match the firearm that shoots it? If they do not match, what could go wrong? Forensic Science: Fundamentals & Investigations, Chapter 17 17

What happens to bullets when they are fired? bsapp. com

Pull the Trigger and. . . 1. A pin strikes the primer causing a spark. 2. The powder is then ignited causing an explosion. 3. This explosion pushes the bullet down the barrel bsapp. com

Down the Barrel 4. As a bullet travels down the barrel , it is twisted by the lands and grooves of the barrel. bsapp. com

Out of the Barrel 5. This rifling causes the bullet to exit in a spiral motion bsapp. com

Bullet Analysis & Comparison What are some characteristics used to identify & compare bullets? bsapp. com

Striations bsapp. com

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Matching Procedure Fire bullets from a suspected weapon into water or gel Use comparison microscope, compare these “test fires” to the suspected bullets Striations must be identical for a positive match bsapp. com

Comparison Microscope Two scopes One Field bsapp. com

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What happens to a bullet when it hits a target? • Most bullets tend to mushroom when they hit a target. • Some bullets nearly disintegrate. • Left are bullet fragments from a ½ jacketed hollow point. bsapp. com

Not all bullets mushroom the same. A lot depends on the speed and shape of the bullet, and the characteristics of the target. bsapp. com

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Some more bullets recovered after firing The striations from the rifling are bsapp. com still visible

Gunshot Residues Chemical testing often can detect gun shot residue even if removal is attempted. What does this mean for investigation? Forensic Science: Fundamentals & Investigations, Chapter 17 36

Databases Like fingerprints, there is a federal database for firearms used in previous crimes – NIBIN (National Integrated Ballistics Network). Forensic Science: Fundamentals & Investigations, Chapter 17 37

Kick back https: //www. youtube. com/watch? v=wr. Impek 3 b. I Forensic Science: Fundamentals & Investigations, Chapter 17 38