Firearms: A Quick History 1.Almost every gun is based on the same simple concept: You apply explosive pressure behind a projectile to launch it down a.

Firearms: A Quick History1. Almost every gun is based on the same simple concept: You

apply explosive pressure behind a projectile to launch it down a barrel.

2. The earliest & simplest application of this idea is the cannon. 3. The 1st handheld guns were essentially mini-cannons; you

loaded some gunpowder & a steel ball & lit a fuse

4. War typically resulted in the need for improved weapons technology.

5. In the late 1800’s, the revolver quickly became popular due to it’s size & quick loading.

• It only had to be reloaded every 5-6 shots instead of after each shot.

6. Handguns reigned supreme for the past 200 years & to this day, remain the most popular & readily available firearm.

The Second Amendment

• The Second Amendment to the Constitution gives Americans the right to keep and use guns.

• This right includes non-Americans with visas in some states, but not all states.

• You can lose your gun rights if you are convicted of a crime.

• You MUST have a LICENSE to own a gun, and your weapon must be REGISTERED!

• Americans are “gun nuts” in a lot of ways – we really, really love guns and have many in our country. Be careful!

Gun Ranges

Many states allow those without gun licenses to shoot guns at a gun range. Make sure you know your state’s laws. Many gun ranges offer gun instructors to teach you to shoot. You can also rent many guns to shoot at the gun range.

Types of Firearms

1. Handguns (pistols) – Revolver – Semiautomatic

2. Rifles

3. Shotguns

4. Air or BB guns

Ammunition

Components

1.Cartridge case

2.Primer

3.Propellant

4.Projectile

Bullets

• Made of lead, sometimes jacketed with brass, copper, or steel

• Bullet size—diameter (caliber or gauge)

• Shapes

Pulling the Trigger

1. Pulling the trigger releases the firing pin…2. The firing pin strikes the primer…3. The primer ignites the gun powder…4. The powder generates gas that propels the

bullet forward through the barrel & ejects the spent cartridge case.

• How a Revolver Works - YouTube.wmv• HOW A GUN WORKS - YouTube.wmv• How A Glock Works - YouTube.wmv

Bullet Caliber1. Caliber: the diameter of the gun barrel.2. Caliber is recorded in

– hundredths of an inch (.22 & .38)– millimeters (9mm)

Bullet Anatomy

Cartridge Parts & How it works

Anatomy of a Bullet

Bullet Comparisons

1. Each gun leaves distinct markings on a bullet passing through it.

2. A gun barrel is made from a solid bar of steel that has been drilled/hallowed out.

3. The drill leaves microscopic marks on the barrel’s inner surface.

4. Gun manufacturers also add spiral grooves to the barrel. This is known as rifling.

5. Lands: the space between the grooves.6. As a spinning bullet passes through the barrel, it is

marked by these grooves.

Rifling

1. The grooved spirals inside the barrel of a gun that produce lands and grooves on a bullet

2. Lands & grooves are class characteristics

Striae

1. Scratches on a fired bullet,2. like a barcode3. Can serve as individual

evidence4. Matching bullets or bullet to

a firearm

Class Characteristics1. Class Characteristics: Once a manufacturer chooses a

rifling process, for a particular class of weapon, they keep it consistent.

2. Lands & Grooves are the same for a model. – .32 caliber Smith & Wesson has 5 lands & grooves twisting to

the right.– .32 caliber Colt has 6 lands & grooves twisting to the left.

3. Guns are named based on the size of bullets they are designed to fire. Don’t use the wrong size ammunition, as the gun won’t perform as designed.

Cartridge Case

1. Usually brass or nickel-clad brass

2. Class evidence – Manufacturer– Shape– Caliber– Composition

Head Stamps

Rimfire & Centerfire Cartridges

Breech Marks1. When a cartridge is fired, the explosion forces the bullet down the

barrel and the shell casing is forced back against the breech. 2. This leaves impressions unique to the individual gun’s breech on

the shell casing.

Breech face Marks

Actual Breech Marks

Firing Pin Marks1. In order to fire the

cartridge, the primer must first be ignited. To accomplish this a firing pin strikes the center ring of the cartridge.

2. This will in turn leave a distinct impression that is unique to the firing pin of that particular gun.

Firing Pin Marks

Chamber Marks

Ejector Marks

ShotgunsShotguns1. Smooth barrel

– Projectile NOT marked as it passes through

2. Fire small lead balls or pellets contained within a shell.

3. Characterized by:– diameter of the shot– size & shape of the wad– Gauge: diameter of the barrel

( gauge diameter)

4. Identification can still be made by comparison of extractor/ejector markings on shotgun shell.

Features of a Semiautomatic Handgun

SERIAL NUMBER RESTORATION1. When a serial number is stamped into a gun,

the metal underneath the number is compressed & hardened.

2. If the number is filed-off, the hardened area may still be present.

3. By using an acid solution the metal can be slowly eaten away.

– In this process the softer metal will be eaten away first and the number may reappear.

4. Serial Numbers/Restoration of serial numbers

– Items of value may have ID numbers stamped into them.

– Grinding is usually used to obliterate identification numbers.

– To restore ID numbers on metal, an acid etching solution is employed.

HCl-CuCl2

Firearm Safety Tips Firearm Safety Tips

•Don’t buy a gun unless you know how to use it safely.

•Store it unloaded and locked up. •Lock it out of children’s reach. •Lock up ammunition separately from the

gun.•Keep trigger locks on your guns for extra

prevention, or disassemble your gun completely.

EpidemiologyEpidemiology

•Everyday 11 people under 19 are killed by firearms.

•1968 to 1991 study, firearm-related deaths in 1991 exceeded the number of motor vehicle related deaths in the United States.•Firearm related injuries are the second leading cause of death for children ages 10-14 yrs.•It is estimated that the number of children sustaining non-fatal firearm injuries is four to five times greater than the number of children who die from such injuries each year.

•Handguns account for the majority of firearm related injuries in the United States.

Firearm Injury Statistics

Epidemiology Cont’dEpidemiology Continued

•Approximately 50% of all US homes have a firearm.

•Over 50% of handguns are stored loaded or with the ammunition.

•Keeping a gun in the home increases the chances of a homicide by three times and increases the chances of a suicide by five times.

•A gun kept in a household is 43 times more likely to kill someone that the family knows than to kill someone in self-defense.

•77% of violent deaths in schools are caused by firearms.

Firearm Prevalence Statistics

12 golden rules for safe gun handling

1. Always treat the gun as loaded.2. Always keep the gun pointed in a safe direction.

3. Always keep your finger straight and off the trigger until you are ready to shoot.

4. Always keep the gun unloaded until your are ready to shoot it.5. Never point the gun at anything you don’t intend to destroy.

6. Be certain of your target and what is beyond it, and never shoot at sound.7. Learn the mechanical and handling characteristics of your gun before you

use it.8. Always use the proper ammunition.

9. Be sure the barrel is clear of obstructions before loading and shooting.10. If your gun fails to fire when the trigger is pulled, hold your shooting

position for a few seconds, then with your muzzle pointed in a safe direction, unload the gun.

11. Don’t rely on the gun’s safety to keep it from firing.12. Be aware of your surroundings when handling guns so you don’t trip or

lose your balance and accidentally point and/or fire the gun at anyone or anything.

Gun Culture

• Guns are a part of American culture, but that doesn’t mean that all Americans like guns, use guns, or are safe around guns.

• If you have a friend who handles guns without following the 12 golden rules, STAY AWAY from them when they have a weapon!

• Remember that a gun is a WEAPON, not a TOY! BE CAREFUL!

Kinds of Carry

Open Carry• Only allowed in some states• Having a gun with you that

is clearly visible

Concealed Carry• Allowed with a PERMIT in

most states• Having a gun with you that

is under your clothes/in your purse/cannot be seen

Transporting Guns

• State and local laws about guns vary.• DO NOT EVER move a gun across a state line

without a special permit• DO NOT EVER have a gun without a permit

FOR YOUR STATE• DO NOT EVER cross an international border

with a gun (even if it is just in your friend’s car)