CRI 414 3RD EXAM PART 2

A detailed diagram of a rifled barrel with annotations explaining the rifling process, surrounded by various bullets and cartridge cases.

Advanced Firearm Identification Quiz

Test your knowledge on forensic firearms examination with our Advanced Firearm Identification Quiz. This quiz contains 32 carefully crafted questions that explore the intricacies of firearm identification, ballistics, and rifling techniques.

  • Assess your understanding of key concepts in gun science.
  • Learn about the components and markings that help identify firearms.
  • Challenge yourself or others interested in forensic science.
32 Questions8 MinutesCreated by ShootingStar247
In 1929 the _____________ led to the opening of the first independent scientific crime detection laboratory in the United States.
St. Valentine's Day Massacre
Maguindanao massacre
Manila massacre
Palawan massacre
When a bullet is fired through a rifled barrel, the raised and lowered spirals of the rifling scrape fine grooves called__________ or (markings) into the bullet.
Striations
Rifling
Lapping
Reaming
Current production M16 rifle uses a ___________ inch twist,
1 in 7
1 in 9
1 in 8
1 in 6
Civilian AR-15s and the current Mini-14 use a __________ inch twist
1 in 7
1 in 9
1 in 8
1 in 6
Marlin Firearms use a distinctive _______ Micro-Groove rifling in many of their firearms
16-groove
12-groove
6-groove
8-groove
A tool with a series of cutting edges with slightly increasing height that are used to cut the spiral grooves in a barrel, all grooves are cut with a single pass of the broach.
Broach Gang
Broach Single
Button
Hook
A hardened metal plug with a rifled cross section configuration. It is pushed or pulled through a drilled a reamed barrel in order to cold form the spiral grooves to the desired depth and twist.
Broach Gang
Broach Single
Button
Hook
A non adjustable rifling cutter that cuts all of the grooves simultaneously, use in a series of increasing dimensions until the desired grooves depth is achieved.
Broach Gang
Broach Single
Button
Hook
Is a cutting tool that has a hook shape and only cuts one grove at time
Broach Gang
Broach Single
Button
Hook
A cutting tool that cuts two opposing grooves at one time
Scrape
Swage
Breech markings
Bullet marking
An internal mandrel with a rifling configuration that forms rifling in a barrel through external hammering
Scrape
Swage
Breech markings
Bullet marking
Marks on the cartridge case can be matched to marks in the chamber and breech. For a number of reasons, Cartridge cases are often easier to identify than bullets.
Scrape
Swage
Breech markings
Bullet marking
Caused by the lands
Land marks
Groove marks
Skid marks
Stripping marks
An elevated or negative impression caused by the grooves.
Land marks
Groove marks
Skid marks
Stripping marks
Due to worn out barrel. A marks that appear on the bearing surface near the nose of the bullets
Land marks
Groove marks
Skid marks
Stripping marks
due to bullet “jumping” the refilling land and groove marks are called “rifling marks”. These are found on the cylindrical or peripheral surface of the fired bullets and caused by rifling inside the gun barrel. Also generally found on bullets fired through “loose fit” barrels wherein the rifling is already worn out.
Land marks
Groove marks
Skid marks
Stripping marks

a partial shaving near the nose of fired bullet, resulting from cylinder misalignment in a revolver. Also known as shearing marks.

Shaving marks
Breech face marks
Chamber marks
Ejector marks
A microscopic of the firearms breech face found on the base of the fired cartridge case and primer after firing.
Shaving marks
Breech face marks
Chamber marks
Ejector marks
A microscopic marks left on a cartridge case by the chamber wall, which the result of any or all of the following; loading expansion of the cartridge case against the chamber wall during firing and extraction.
Shaving marks
Breech face marks
Chamber marks
Ejector marks
A microscopic marks that left on the head of cartridge case, generally near the rim, resulting from contact with the ejector and it is commonly found in an automatic firearm such pistol and rifle this type of marks can be use to determined the position of the cartridge during firing
Shaving marks
Breech face marks
Chamber marks
Ejector marks
A microscopic marks that left on the cartridge case which come into contact with the extractor and commonly found ahead of the rim extracting grooves of the cartridge.
Extractor marks
Chamber marks
Shaving marks
Ejector marks
The diameter in which the bore was reamed. It is the distance measured between two opposite lands inside the bore.
Bore diameter (caliber)
Number of lands and grooves
Width of lands
Width of grooves
the number of lands and grooves inside the bore of a fired firearm are always the same.
  1. LANDS – the elevated portions.
  2. GROOVES – the depressed portion.
TRUE
FALSE
land width is dependent on the bore diameter, groove width and number. The lands are “reminder” of the circumference after subtracting all the groove widths.
Width of lands
Width of grooves
Number of lands and grooves
Bore diameter (caliber)

is measure as the “shortest” distance between the two side or edges of a groove.

Width of lands
Width of grooves
Number of lands and grooves
Bore diameter (caliber)

the rifling inside the gun barrel may twist either to the right or left. The twist of the rifling cause the bullet to rotate as it passes through the bore for the bullet to have “gyroscopic stability” during its flight from muzzle to target.

Width of lands
Width of grooves
Bore diameter (caliber)
Direction of twist

it is a measure of the twisting of the lands and grooves. It refers to the “distance” advanced by the rifling’s in one complete run.

Pitch of rifling
Width of grooves
Bore diameter (caliber)
Direction of twist

groove depth in the bore is measured on a radius of the bore as seen in cross section. Grooves are usually a few thousands of an inch deep. It is equal to the “height” of the side of a “land”.

Pitch of rifling
Depth of grooves
Bore diameter (caliber)
Direction of twist

those characteristics that are determinable even prior to the manufacture of the firearms. These characteristics are factory specifications and

within the control of man.

Class characteristics
Individual characteristics
Attitude characteristics
Direction of twist

are those characteristics markings peculiar and not found in all other firearms. They serve as basis to identify a particular firearm. The individual characteristics are determinable only after the manufacture of the firearm.

Class characteristics
Individual characteristics
Attitude characteristics
Direction of twist
Principles involves in Shell Identification
The breech face and striker (or firing pin) of very single firearm have microscopic individualities of their own.
Every firearm leaves its “fingerprint” or “thumb mark” on every cartridge it fires
The whole principle of identification of shells is predicated or based on the fact that since the breech face of every weapon must be individually distinct, the cartridge cases which it fires are imprinted with this individuality.
No two barrels are microscopically alike or identical as the internal surface of the bore or barrels all possess individual and characteristics markings in their own.
Every barrel leaves its “thumb mark” or “fingerprint” on very bullet on it
Principles Involved in Bullet Identification
No two barrels are microscopically alike or identical as the internal surface of the bore or barrels all possess individual and characteristics markings in their own.
When a bullet is fired from the fired gun barrel, it becomes engrave by the ruling’s and these engravings will vary in its minute details with every individual firearm.
Every barrel leaves its “thumb mark” or “fingerprint” on very bullet on it
Every barrel never leaves its “thumb mark” or “fingerprint” on very bullet on it
Two barrels are microscopically the same as the internal surface of the bore or barrels all possess individual and characteristics markings in their own.
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