forensics - arson and firearms
cartridge
a case usually made of brass or copper containing the power charge the primer and the bullet
griess test
a chemical test used to develop patterns of gunpowder residues around bullet holes. presence of nitrites
comparison microscope
a compound microscope that allows the side-by-side comparison of samples, such as of hair or fibers
spontaneous combustion
a fire caused by a natural heat-producing process in the presence of sufficient air and fuel
pistol
a firearm designed to be held and fired with one hand
shotgun
a firearm with a smooth bore designed to fire small pellets called shot or rifled slugs.
revolver
a pistol having a revolving cylinder with several cartridge chambers that may be fired in succession
rifle
a shoulder firearm with a rifled barrel designed to fire one projectile at a time
firearm
a weapon capable of firing a projectile using a confined explosive as a propellant (pistol or rifle)
high explosives
an explosive with a velocity of detonation greater than 1,000 meters per second
low explosives
an explosive with a velocity of detonation less than 1,000 meters per second ex: fireworks
tool marks
any impression, scratch or abrasion made when contact occurs between a tool and an object
IBIS
computerized image analysis system that records striated images from bullets and cartridge cases for comparison in a national database
gunshot residue
consists of burned and unburned gunpowder, vaporized and particulate lead, primer residues of lead, barium and antimony
fully automatic weapon
continuously fires rounds while the trigger is pressed and held.
incendiary devices
devices specifically created to start fires, such as a Molotov Cocktail
semiautomatic weapon
fires one round with each individual trigger pull
indentation marks
made when a tool is pressed against a softer surface
abrasion marks
made when one surface slides across another
gunpowder
main propellent in modern firearms
gauge
measurement of shotgun to develop patterns of gunpowder residues around bullet holes
cutting marks
produced along the edge as a surface is cut
combustion
rapid combination of oxygen with another substance, accompanied by production of noticeable heat and light
grooves
spiral cuts into the bore of a barrel that give the bullet its spin or rotation as it moves down the barrel
rifling
spiral grooves cut into the inside barrel surface to cause a bullet to spin, thereby stabilizing it
oxidation
the combination of a substance with oxygen
caliber
the diameter of the bore of a rifle before the rifling grooves are cut
deflargation
the extremely rapid burning of a material that is much faster than normal combustion, but slower than detonation
muzzle
the forward end of a barrel.
barrel
the metal tube of a firearm made from iron or steel, through which the bullet or shot charge passes when the firearm is fired
flashpoint
the minimum temperature at which a liquid fuel produces enough vapor to burn
firing pin
the part of the breech mechanism which strikes the primer of the cartridge.
magazine
the part of the repeating firearm which holds the cartridges or shells in position ready to be loaded one at a time into the chamber
trajectory
the path a bullet travels from muzzle to impact
lands
the raised areas between two grooves in the rifling of a gun barrel that impart grooves on the bullet
ballistics
the study of what happens to moving projectiles in the barrel and in flight; their trajectory, force, impact and penetration
bore
the tunnel down the barrel of a firearm through which the projectile travel
sodium rhodizonate testing
used to detect lead residues
accelerant
wany material used to start or sustain a fire
auto-ignition temperature
when an object, such as wood, reaches this type of temperature, it will combust or burn in the air without a spark or ignition source: