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Question. The inner surface of the barrel of a gun leaves its markings on a bullet passing through it. These markings are peculiar to each gun. Would these markings be considered class characteristics or individual characteristics?. Answer.
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Question • The inner surface of the barrel of a gun leaves its markings on a bullet passing through it. These markings are peculiar to each gun. Would these markings be considered class characteristics or individual characteristics?
Answer • Both. The lands, grooves and twists are class evidence while the microscopic striations are considered individual evidence.
Question • What is the purpose of rifling, or impressing the inner surface of a barrel of a gun with spiral grooves?
Answer • The grooves serve to guide a fired bullet through the barrel, imparting a rapid spin to insure accuracy and optimum distance.
Question • The surfaces of the original bore remaining between the grooves are called __________.
Answer • Lands
Question • The diameter of the gun barrel, measured between opposite lands, is known as _____.
Answer • caliber
Question • True or False? • Once a manufacturer chooses a rifling process, the class characteristics of the weapon’s barrel will remain consistent, each will have the same number of lands and grooves, with the same approximate width and direction of twist.
Answer • True
Question • True or False? • No two rifled barrels, even those manufactured in succession, will have identical striation markings.
Answer • True
Question The single most important tool to a firearms examiner is the ____________.
Answer • Comparison Microscope
Question Unlike rifled firearms, a shotgun has a • ____________ barrel.
Answer • smooth
Question • The diameter of the shotgun barrel is expressed by the term _________.The ________ this number is, the _________ the barrel’s diameter.
Answers • Gauge • Higher • smaller
Question • The shape of the _______________will be impressed into the relatively soft metal of the primer on the cartridge case.
Answer • Firing pin
Question • The cartridge case, in its rearward thrust, is impressed with the surface markings of the _________________.
Answers • breechblock
Question • What do you call the rear part of a firearm barrel?
Answer • The Breechblock
Question • The interior of a firearm barrel.
Answer • Bore
Question • The cut or low-lying portions between the lands in a rifled bore.
Answer • Grooves
Question • The spiral grooves formed in the bore of a firearm barrel that impart spin to the projectile when it is fired.
Answer • Rifling
Question • Factors such as barrel length, caliber, type of ammunition, and type and condition of the weapon fired influence the amount of gunpowder residue deposited on a target. True or False?
Answer • True
Question • Distinctive markings that may appear on the shell as a result of metal to metal contact can be caused by the _____________which is the mechanism in a firearm that throws the cartridge or fired case from the firearm.
Answer • Ejector
Question • Distinctive markings that may appear on the shell as a result of metal to metal contact can be caused by the __________which is the mechanism in a firearm by which a cartridge of a fired case is withdrawn from the firing chamber.
Answer • Extractor
Question • Distinctive markings that may appear on the shell as a result of metal to metal contact can be caused by the __________which is the mechanism that in a firearm holds the bullets.
Answer • Magazine or clip
Question • These are fine lines found in the interior of the barrel. They are impressed into the metal as the negatives of minute imperfections found on the rifling cutter’s surface, or they are produced by minute chips of steel pushed against the barrel’s inner surface by a moving broach cutter.
Answer • Striations
Questions • During the initial phase of comparison between an evidence bullet and a test-fired bullet, what characteristics are often looked at first?
Answer • Class characteristics such as grooves, lands and twists.
Question • Not only must the lands and ___________ of the test and evidence bullet have identical widths, but the ____________________ striations on each must coincide.
Answer • Grooves, • Longitudinal
Question • The NIBIN was eliminated the need for forensic ballistic specialists. True or False?
Answer • False - the ultimate decision for making a final bullet comparison will be determined by the forensic examiner through traditional microscopic methods.
Question • This network produces database files from • bullets and cartridge casings retrieved from • crime scenes or test fires from retrieved firearms, often linking a specific weapon to multiple crimes.
Answer • The National Integrated Ballistics Information • Network, NIBIN
Question • A star-shaped (stellate) tear pattern around the bullet hole entrance, surrounded by a rim of a smokeless deposit of vaporous lead usually indicates a weapon discharge of ________________ from the target.
Answer • Of less than one inch