Ch. 8 Firearms Flashcards
acid etching method
a method in which strong acid is applied to a firearm to reveal the serial number
black powder
the oldest gunpowder, which was composed of a mixture of potassium nitrate (saltpeter), charcoal, and sulfur
bore
the interior of a gun barrel
breechblock
the metal block at the back end of a gun barrel
broach cutter
a tool that is pushed through the gun barrel to form the rifling
caliber
the diameter of the bore of a firearm (other than a shotgun)
- usually expressed in hundredths of an inch (0.38 caliber) or in millimeters (9 mm)
cartridge
ammunition enclosed in a cylindrical casing containing an explosive charge and a bullet, which is fired from a rifle or handgun
choke
a device placed on the end of a shotgun barrel to change the dispersion of pellets
ejector
the mechanism in a semiautomatic weapon that ejects the spend cartridge from the gun after firing
external ballistics
a description of the events that occur after the bullet leaves the barrel of the gun but before it strikes its target
extractor
the device that extracts the spend cartridge from the gun’s chamber
gauge
the unit used to designate size of a shotgun barrel
- the interior diameter of a shotgun barrel is determined by the number of lead balls that fit exactly in the barrel and are equivalent to 1 lb
grooves
the cutout section of a rifled barrel
internal ballistics
a description of the events that transpire within the firearm
lands
the raised section of a rifled barrel
Magnaflux method
a method of restoring a gun’s serial number
nitrocellulose
a cotton-like material produced when cellulose is treated with sulfuric acid and nitric acid
- aka guncotton
- used in the manufacture of explosives
nitroglycerin
an explosive chemical compound obtained by reacting glycerol with nitric acid
- used in the manufacture of gunpowder and dynamite
primer
an igniter that is used to initiate the burning of gunpowder
rifling
the spiral grooves on the inside surface of a gun barrel that make the bullet spin
semiautomatic pistol
a firearm that fires and reloads itself
smokeless powder
an explosive charge composed of nitrocellulose or nitrocellulose and nitroglycerin (double-base powders)
striations
fine scratches left on bullets
- formed from contract of the bullet with imperfections inside the gun barrel
terminal ballistics
a description of what happens when the bullet strikes its target
wad
a plastic, cardboard, or fiber disk that is placed between the powder and the shot in a shotgun shell
The accuracy of a firearm can be greatly improved by making the barrel ________ (longer/shorter).
longer
The spiral grooves in a gun barrel are referred to as ________.
rifling
The rifling on the interior of a gun barrel has spiral grooves and ________.
lands
The diameter of a gun barrel, as measured from a land on the left to one on the right, is known as the ________ of a weapon.
caliber
A broach cutter is used to cut the _________ in the interior of the gun barrel.
grooves
The lands and grooves in a gun barrel are ________ (class/individual) characteristics.
individual
Besides grooves, the broach cutter produces fine lines called _________.
striations
As bullets emerge from the gun barrel, they rotate, a phenomenon that is called _______.
precession
The kinetic energy of a bullet ________ (increases/decreases) as the caliber of the weapon increases.
increases
The diameter of a shotgun barrel is expressed as a(n) _________.
gauge
The higher the shotgun gauge, the _______ (larger/smaller) the diameter of the barrel.
smaller
A sawed-off shotgun is one that has a barrel length less than ________ inches.
18
In the past, lead was used to make bullets because it has a high ________.
density
Lead’s low ______ makes it soften at higher velocities.
melting point
The element _________ is added to lead to raise its melting point.
antimony (Sb)
The jacket of a cartridge is made from ________ or ________.
copper or brass
Black powder is a mixture of _________, _________, and ________.
charcoal (C), sulfur (S), and potassium nitrate (KNO3)
Smokeless powder is made from the chemicals ________ and ________.
cordite and ballistite
Nitroglycerin is desensitized by adding _______, ________, or _______.
10%-30% ethanol, acetone, or dinitroluene
The primer of a cartridge holds a(n) _________ explosive mixture.
stable but shock-sensitive
The ________ was a crucial invention needed to make a gun that would fire in any weather.
primer
Many firing ranges have banned ________ primers because of their potential health risks.
lead
In a shotgun shell, the _________ is designed to make an almost gas-tight seal with the barrel.
wad
The matching of fired bullets is carried out by using a(n) _________ microscope.
comparison
IBIS is an acronym for _________.
Integrated Ballistics Identification System
Serial numbers on handguns can be restored by two methods: the ________ method and the _______ method.
magnaflux; acid etching
