20Databases on the patterns of spiraling grooves kept by FBI Bureau of Alcohol, Tobacco and Firearms (ATF)Spacing and direction(clockwise or counterclockwise)of the lands and grooveson a slug along with caliber…Examiner knows exactly what brand of weapon
22The Magnus effect is the phenomenon whereby a spinning object flying in a fluid creates a whirlpool of fluid around itself, and experiences a force perpendicular to the line of motion. Wikipedia (knuckleball)
23Smooth bore weapons such as shotguns have no rifling.
25The cartridge is plastic, with shot, propellant, and primer. Wads are pieces of paper, cardboard or cotton to keep materials from mixing.
26The primer is lit mechanically when struck by the firing pin. Primer ignites, burns, fast and hot Sets off the propellant whichPushes the shot out of the barrelSHOTGUN!
27Not all firearms eject spent cartridges But all eject gun shot residue GSRGSR contains specific chemicals:lead, barium and antimony, the materialof primer mixturesGSR shows metal content andmanufacturers use metaladditives in known proportions
28The other type of ammunition has a single , solid projectile in a cartridge. The cartridge case is called a ‘jacket’ surrounding a metal core called the ‘slug’.
29A modern cartridge consists of the following: 1 A modern cartridge consists of the following: 1. the bullet itself, which serves as the projectile; 2. the case, which holds all parts together; 3. the propellant, for example gunpowder or cordite; 4. the rim, part of the casing used for loading; 5. the primer, which ignites the propellant.
30Forces cause the projectile , the slug, out the open end of the barrel.Energy is required to throw a slug which producesnoise and heat, which deforms the metals of the slugs.
36The heated slug spins along the rifling inside the barrel and picks up the riflings, impressions. Slug recovered at crime scene, will bear same markings on it cartridge as found on the inside of boreonly reverse of …Lands are raised areas and grooves are depressions on the metalSlugs deform as they hit objects.
39GaugeMeasure of shotguns only;shot to an equivalent slug12 gauge shotgun packs a load equivalent to a solid lead slugweighing 1/12 of a pound10 gauge; load weighing 1/10 of a poundHigher # ,lighter the load
40Caliber is measure of bore of weapons; handguns and rifles Measure in 1/100ths of an inch..45 caliber handgun bore is 45/100 of 1 inch.Magnum is not a caliber but a description of firepower of propellant.44 magnum and 45 caliber weapons and ammunition are not interchangeable… different propellant
419 mm caliber is a metric measurement. Originally made by European gun manufacturers.Measures the caliber of a gun in mm not inches.
42FBI, ATF (Alcohol, Tobacco and Firearms) Government agencies establisheddatabases of patterns of grooves in guns.Lands and grooves on gun, match lands and grooves on gun and evidence is individualistic for a gun.Can also tell manufacturer, type, size of gun
43Valuable forensic evidence Firing pin marks on the breach face of the cartridge reveals specific markings to a particular gunWhere cartridge lands, is left… where is shooter?
44Not all firearms eject cartridges.. All eject gunshot residue (GSR)vapor, particulates, heated chemicals, lead barium, antimonyIf found on suspect means:-they fired weapon-were present when fired or-handled a recently fired weaponIndividual ammunitions composition varies with manufacturer…Can trace ammo or batches of ammo
45In the field of forensic science, forensic ballistics is the science of analyzing firearm usage in crimes.
47THERE IS A METHOD TO THE MADNESS…. Energy Calculator Example: The muzzle energy of a 300 Remington Ultra Mag 180gr Core-Lokt Ultra bullet propelled at 3250 feet per second is determined using the follow formula: M x V2 ÷ = foot pounds energy.Step 1: Multiply M (M = bullet weight in grains) times V2 (V2 = the square of bullet velocity in feet per second): 180 x 3250 x 3250 = 1,901,250,000Step 2: Divide the product of step 1 by : 1,901,250,000 ÷ = 4221 foot pounds of energy.
48Gun powder and particles residue indicates proximity to victim and angle of entry wound.
50Armor piercing shell of the APBC 1 Light weight ballistic cap 2 Steel alloy piercing shell 3 Desensitized bursting charge (TNT, Trinitrophenol, RDX...) 4 Fuse (set with delay to explode inside the target) 5 Bourrelet (front) and driving band (rear)