unit 13 firearms

Question 1

Ballistics

Answer 1

the study of bullets and firearms

Question 2

Firearm

Answer 2

A weapon capable of firing a projectile using a confined explosive as a propellant

Question 3

bullet

Answer 3

The projectile that is released when a firearm is discharged

Question 4

caliber

Answer 4

The bore diameter of a rifled firearm, usually expressed in hundredths of an inch or millimeters – for example, .22 caliber or 9 millimeter

Question 5

Who invented gunpowder?

Answer 5

Wei Boyang (chinese monk)

Question 6

Who invented the first revolver?

Answer 6

Samuel Colt, Robert Adams, Francesco Antonio, Daniel Leavitt

Question 7

What two types of muzzle-loader weapons existed before the invention of percussion firing?

Answer 7

flintlock and matchlock firearms

Question 8

Distinguish between a rifle and a shotgun.

Answer 8

A rifle is a firearm that has a long barrel; a long gun
A shotgun uses shell ammunition that contains numerous ball-shaped projectiles, called shot

Question 9

What is the purpose of “rifling”?

Answer 9

is to improve the accuracy and range of a projectile fired from a firearm.

Question 10

Distinguish between a revolver and a semi-automatic

Answer 10

Revolver – a pistol with a revolving cylinder (features several firing chambers within a revolving cylinder
Semiautomatic – a pistol with a clip-fed mechanism that fires one shot per pull of the trigger; the empty cartridge ejects, and the next cartridge advances automatically (features a removable magazine

Question 11

Distinguish between semi-automatic and fully automatic weapons.

Answer 11

1. Semiautomatic – a pistol with a clip-fed mechanism that fires one shot per pull of the trigger; the empty cartridge ejects, and the next cartridge advances automatically (features a removable magazine)
2. Fully-automatic – a firearm with a clip-fed mechanism that fires repeatedly and for as long as the trigger is held down

Question 12

Name and describe the purposes of the four (4) different types of bullets.

Answer 12

1. Full metal jacket (FMJ) bullets: These bullets are designed to penetrate targets without expanding or deforming, making them a good choice for target shooting or practice.
2. Hollow point (HP) bullets: HP bullets have a hollow cavity at the tip that is designed to expand upon impact with a target, creating a larger wound channel and increasing the chances of stopping the target.
3. Soft point (SP) bullets: SP bullets have a lead core that is exposed at the tip, which allows them to expand upon impact with a target. The jacket around the bullet is usually thinner than that of an FMJ, which allows for more rapid expansion upon impact.
4. Armor-piercing (AP) bullets: AP bullets are designed to penetrate hard surfaces, such as body armor or steel plate. They typically have a core made of tungsten or another hard material, and a jacket made of copper or other metal.

Question 13

Name the seven(7) common caliber families.

Answer 13

.22 caliber family,9mm family .38 caliber family.40 caliber family.45 caliber family .30 caliber family .50 caliber family

Question 14

Name at least 4 members of the .38 caliber family.

Answer 14

.38 special, .357 magnum, .38 S&W, .380ACP

Question 15

List and describe (including responsible agencies for each) the three (3) databases used in forensic firearm examinations.

Answer 15

1. The National Integrated Ballistics Information Network (NIBIN) 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
2. Integrated Ballistics Identification System (IBIS): The IBIS is a database created by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) that contains digital images of fired cartridge cases and bullets.
3. Firearms Reference Collection (FRC): The FRC is a database created by the Federal Bureau of Investigation (FBI) that contains images and data on firearms and ammunition from around the world.

Question 16

Name and describe the four (4) different markings used in ballistics identification and comparisons.Describe where each marking may be found.

Answer 16

Firing pin impression: The firing pin impression is a mark left on the base of a cartridge case by the firing pin of a firearm. The firing pin impression is typically found on the primer of a fired cartridge case.

Extractor mark: The extractor mark is a mark left on the rim of a cartridge case by the extractor of a firearm. The extractor mark is typically found on the rim of a fired cartridge case.

Ejector mark: The ejector mark is a mark left on the side of a cartridge case by the ejector of a firearm. The ejector mark is typically found on the side of a fired cartridge case.

Lands and grooves impressions: The lands and grooves impressions are marks left on the bullet by the rifling of the barrel. The lands and grooves impressions are typically found on the surface of a recovered bullet.

Question 17

What are the major components of gunpowder residue, and what test is typically performed for its detection?

Answer 17

The precise distance from which a handgun or rifle has been fired is determined through careful comparison of the powder-residue pattern located on the victim’s clothing or skin against test patterns the suspect weapon males when fired at varying distances from a target. Chemical tests, such as the Greiss test, may be needed to detect gunpowder residues that are not visible 12. The firing distances for shotguns must again be determined through test firing. The muzzle to target distances can be established by measuring the spread of the discharged shot.

Question 18

What are the components of primer residue? What instrument is used for its analysis?

Answer 18

Examiners measure the amount of barium and antimony on the suspect’s hands,
particularly the thumb web, the back of the hand, and the palm. They may also characterize the morphology of particles containing these elements to determine whether a person has fired, handled, or was near a discharged firearm

Question 19

Explain (including the methods and the principle) how an obliterated serial number can be restored.

Answer 19

Cleaning and Preparation, electrolysis, chemical etching, laser etching. By removing a small amount of metal from the surface, firearms examiners can reveal the underlying serial number and use it to help identify the firearm.