1. Ballistics and Firearms
Ballistics- Study of a projectile in motion
Firearm Identification- Study of whether a bullet or cartridge case was fired from a weapon

2. Firearms
3 categories
Handgun
Rifle
Shotgun

3. Firearms 3 categories: Handguns Revolvers vs. semi-automatics
Revolvers- Rotating cylinder holds the bullets. Consists of 6 individual spaces.
Semi-automatics- Loaded using a magazine/clip. Holds 6-15 rounds

4. Semi-Automatic
The Revolver

5. Firearms Rifles Shotguns Gun with a long rifled barrel
Used for long distance targets
Shotguns
Gun that fires cartridge cases with pellets
Pellets are a.k.a shot
Not a precision weapon because pellets spread out in a circular pattern
Barrels are smooth not rifled and are wider than other gun barrels

6. Shotgun
Rifle

7. Vocabulary
Rifling- Technique of forming grooves in the bore of a barrel to give spin to the bullet
Bore- Interior of barrel
Lands- Raised portion between grooves in bore
Grooves- Cut portions in bore

9. Figure 15–1  Interior view of a gun barrel, showing the presence of lands and grooves.

10. Cross-section of a barrel with six grooves
Cross-section of a barrel with six grooves. The diameter of the bore is the caliber.

11. Rifling Techniques
Broach Cutting- Steel rings cut into the barrel forming a spiral bore
Button Technique- Steel button is forced under high pressure into the barrel
Mandrel Technique- Rod of steel with a shape that’s the reverse of the intended impression is placed in an oversize bore and then it is compressed.

12. Class Characteristics
Characteristics of a class/group of weapons
Number of lands
Number of grooves
Width of lands and grooves
Direction of twist
Rifling technique

13. Individual characteristics
Specific striations that are found on recovered bullets and cartridge casings
Each weapon has a unique bore
Firing pin leaves striations/impressions
Breech Block leaves striations/impressions
Ejector and Extractor leave striations/impressions

14. The Comparison Microscope
Both the evidence bullet and the test bullet are examined at the same time in the same field of view
One bullet is rotated until a well-defined land or groove is found

15. Caliber vs. Gauge Caliber- Measurement of the diameter of the bore.
Expressed in hundredths of an inch or mm
.35 Caliber or 9mm
Gauge- Measurement or size designation of a shotgun. Number of lead balls that fit inside a shotgun barrel (equal to the interior diameter of barrel)
Shotgun barrels are smooth not rifled
As Gauge increases, barrel diameter decreases

17. *The systems could not work together.
Databases
IBIS (Integrated Ballistic Identification System) – Database developed for the Bureau of Alcohol, Tobacco, Firearms and Explosives branch of the government.
DRUGFIRE – Automated search system developed for the FBI.
*The systems could not work together.
NIBIN (National Integrated Ballistic Information Network) – Was created to integrate IBIS & DRUGFIRE

18. Entry Wounds and Muzzle Distance of handgun or rifle
If the muzzle is 2 or more ft. away from the victim the entrance wound is a small hole w/ a bruise called an abrasion collar surrounding it.

19. 2. If the muzzle is between 6 in. and 2ft
2. If the muzzle is between 6 in. and 2ft. The wound appears “tattooed” from the gun powder
Known as stippling

20. 3. If the muzzle is less than 6 in
3. If the muzzle is less than 6 in. from the victim the wound has a compact area of stippling, surrounded by bright red tissue.

21. 4. If the gun is fired at “point blank” range hot gases and gun powder are driven directly into the skin .The skin is scarred into a star shaped pattern.

22. Additional Info

23. Collection & Preservation of Evidence
Firearms:
Unload weapon and record the position of hammer and safety
Record the location of all fired and unfired ammunition in weapon
Mark chamber position on a revolver. For automatic weapons, remove magazine check for prints
Place each round in a separate envelope
Label firearm with tag attached to trigger guard. Include serial number, make , model, and your initials

24. Ammunition
Free bullets from target by carefully breaking away surrounding material- avoid direct contact with bullet
Bullets are individually wrapped in tissue and placed in envelope

25. EXAMPLE NOTES
Chamber Position/ Condition Cartridge/ Headstamp
1 Fired U.S.C. Co.
2 Fired REM-UMC
3 Fired WRA
4 Misfired D.C. Co.
5 Loaded WESTERN
6 Loaded PETERS

26. The Basics of Firearms Step 1: The bullet enters the firing chamber.
Step 2: The hammer is drawn back.
Step 3: The trigger is pulled throwing the hammer forward.
Step 4: The hammer or firing pin strikes the primer igniting the gun powder.
Step 5: The gases released from the exploding gun powder drive the bullet down the gun barrel.
Step 6: The breechblock absorbs the recoil and holds the casing in place.
Step 7: The casing is then removed from the chamber by the extractor.
Step 8: The casing is then thrown from the gun by the ejector.