1. Firearms: A Quick History
Almost every gun is based on the same simple concept: You apply explosive pressure behind a projectile to launch it down a barrel.
The earliest & simplest application of this idea is the cannon.
The 1st handheld guns were essentially mini-cannons; you loaded some gunpowder & a steel ball & lit a fuse

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

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

4. 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!

5. 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.

6. Types of Firearms Handguns (pistols) Revolver Semiautomatic Rifles
Shotguns
Air or BB guns

7. Ammunition
Components
Cartridge case
Primer
Propellant
Projectile

8. Bullets Made of lead, sometimes jacketed with brass, copper, or steel
Bullet size—diameter (caliber or gauge)
Shapes

9. Pulling the Trigger Pulling the trigger releases the firing pin…
The firing pin strikes the primer…
The primer ignites the gun powder…
The powder generates gas that propels the bullet forward through the barrel & ejects the spent cartridge case.

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

15. Bullet Caliber Caliber: the diameter of the gun barrel.
Caliber is recorded in
hundredths of an inch (.22 & .38)
millimeters (9mm)

16. Bullet Anatomy

17. Cartridge Parts & How it works

18. Anatomy of a Bullet

19. Bullet Comparisons
Each gun leaves distinct markings on a bullet passing through it.
A gun barrel is made from a solid bar of steel that has been drilled/hallowed out.
The drill leaves microscopic marks on the barrel’s inner surface.
Gun manufacturers also add spiral grooves to the barrel. This is known as rifling.
Lands: the space between the grooves.
As a spinning bullet passes through the barrel, it is marked by these grooves.

20. Rifling
The grooved spirals inside the barrel of a gun that produce lands and grooves on a bullet
Lands & grooves are class characteristics

21. Striae Scratches on a fired bullet, like a barcode
Can serve as individual evidence
Matching bullets or bullet to a firearm

22. Class Characteristics
Class Characteristics: Once a manufacturer chooses a rifling process, for a particular class of weapon, they keep it consistent.
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.
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.

23. Cartridge Case Head Stamps Rimfire & Centerfire Cartridges
Usually brass or nickel-clad brass
Class evidence
Manufacturer
Shape
Caliber
Composition
Head Stamps Rimfire & Centerfire Cartridges

25. Breech Marks
When a cartridge is fired, the explosion forces the bullet down the barrel and the shell casing is forced back against the breech.
This leaves impressions unique to the individual gun’s breech on the shell casing.

26. Breech face Marks

27. Actual Breech Marks

28. Firing Pin Marks
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.
This will in turn leave a distinct impression that is unique to the firing pin of that particular gun.

30. Firing Pin Marks

32. Chamber Marks

33. Ejector Marks

34. Shotguns Smooth barrel
Projectile NOT marked as it passes through
Fire small lead balls or pellets contained within a shell.
Characterized by:
diameter of the shot
size & shape of the wad
Gauge: diameter of the barrel
( gauge  diameter)
Identification can still be made by comparison of extractor/ejector markings on shotgun shell.

35. Features of a Semiautomatic Handgun

38. SERIAL NUMBER RESTORATION
When a serial number is stamped into a gun, the metal underneath the number is compressed & hardened.
If the number is filed-off, the hardened area may still be present.
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.

39. 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

40. 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.

41. Epidemiology Epidemiology Firearm Injury Statistics
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 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.

42. Epidemiology Continued
Epidemiology Cont’d
Epidemiology Continued
Firearm Prevalence Statistics
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.

43. 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.

44. 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!

45. Kinds of Carry Open Carry Concealed Carry Only allowed in some states
Having a gun with you that is clearly visible
Allowed with a PERMIT in most states
Having a gun with you that is under your clothes/in your purse/cannot be seen

46. 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)