Ballistics Veronica Kwok SBF 5 01 Instructor Ms

Ballistics Veronica Kwok SBF 5 -01 Instructor: Ms. Villani

What is Ballistics? • Also known as the Firearms Unit • Science of propulsions, flight, and impact of projectiles Bullet leaves barrel of the gun

Types of Ballistics Internal External Intermediate Terminal Wound Path of a projectile (a bullet)

Internal Ballistics • the propulsion (what happens within the gun) • muzzle velocity – velocity when bullet exits the barrel • pressure generated from the controlled expansion of burning gunpowder

Internal Ballistics: What affects velocity and pressure in a gun? • Capacity of the powder chamber • Relative burning rate and burning characteristics of the propellant powder used • Amount of propellant used and how much it fills the powder chamber • Temperature of the propellant prior to ignition • Barrel freebore • Neck tension

Internal Ballistics: What affects velocity and pressure in a gun? • Diameter, weight, and the bearing length of the projectile • Length and interior dimensions of the barrel • Uniformity and speed of ignition of the propellant powder

External Ballistics • the flight of the projectiles (what happens between the gun and the target) • Bullets don’t typically travel in a straight path • Rotational forces rotational effects on a bullet

External Ballistics: Bullets • striations – minor deformation as the bullet cross the barrel of the gun • caused by rifling (tool marks) (left) Striations of a bullet (right) Rifling

External Ballistics: Bullets • cartridge – single unit of ammunition consisting of the cartridge case, primer, and propellant with/without projectiles Components of a cartridge

Terminal Ballistics • the impact of projectiles (what happens when it hits the target) • When the bullet hits a target, the bullets tend to become distorted (shown below)

Terminal Ballistics • Bullets come in various shapes and sizes so the damage to the bullet after hitting a target may be different; causing the wounds to be different

Wound Ballistics • the mechanism and medical implications of trauma cause by bullets and explosively driven fragments (effects on the body from guns)

Wound Ballistics: Factors that Affect Nature of Wounds • Bullet velocity • Bullet mass • Distance between muzzle and target • Bullet design • Shape • Size • Type of tissue

Wound Ballistics: Damages Caused to Tissue • Laceration/crushing – low velocity bullets, as in handguns, that travel less than 1000 fps do virtually all their damage via crushing. • Shock waves - Shock waves compress the medium and travel ahead of the bullet, as well as to the sides, but these waves last only a few microseconds and do not cause profound destruction at low velocity.

Wound Ballistics: Cavitation • projectiles travelling in excess of 1000 fps • "permanent" cavity – caused by the path of the bullet itself • "temporary" cavity – formed by continued forward acceleration of the medium (air or tissue) in the wake of the bullet, causing the wound cavity to be stretched outward.

Gunshot Residue • When the bullet exits the muzzle, pressure behind it blows the gunshot residues out of the firearm's barrel under high velocity • expelled from the barrel in a smoky cone shaped pattern

Gunshot Residue • Gunpowder residues + lead powder = gunshot residue • Can determine: • Whether or not a person has fired a weapon recently • Distance between shooter and target • Element/metals in the bullet/weapon • Area where bullet is fired

Sources • Slide 2, 3 : http: //search. eb. com/eb/article-9012015 • Slide 4, 7, 8, 9, 10, 11 : "FIREARMS TUTORIAL. " Eccles Health Sciences Library. 05 Apr. 2009 http: //library. med. utah. edu/Web. Path/TUTORIAL/G UNS/GUNBLST. html • Slide 5 : "Internal Ballistics. " FR. FROG'S Home Page. 10 June 2009 http: //www. frfrogspad. com/intballi. htm.

Sources • Slide 6 : "BALLISTICS, . " The History Channel - Home Page. 30 Mar. 2009 http: //www. history. com/encyclopedia. do? article. Id= 202124. • Slide 12, 13, 14, 15 : "Wound Ballistics, Ballistic Injury, Stopping Power, Gunshot Wounds. " Firearms. Tactical. com - Home. 10 June 2009 http: //www. firearmstactical. com/wound. htm. • Slide 16, 17 : Firearms. ID. com- An Introduction to Forensic Firearm Identification. 05 Apr. 2009 http: //www. firearmsid. com/A_bullet. IDcal. htm.

Picture Sources • Slide 1, 2, 4, 12 : http: //www. firearmsid. com • Slide 3 : http: //www. frfrogspad. com/extbal. htm • Slide 6, 7, 8, 10, 11 : http: //library. med. utah. edu/Web. Path/TUTORIAL/G UNS/GUNBLST. html • Slide 8 : http: //www. firearmsid. com/A_Bullet. ID. htm • Slide 9 : http: //www. firearmsid. com/A_bullet. IDcal. htm • Slide 13 : http: //live-life-withhack. blogspot. com/2008/09/hacking. html

Picture Sources • Slide 15 : http: //www. firearmstactical. com/images/Wound%2 0 Profiles/Wound%20 Components. jpg • Slide 16 : www. firearmsid. com/A_distance. GSR. htm • Slide 17 : http: //www. firearmsid. com/A_distance. Exams. htm