Presentation on theme: "Chapter 21 – Firearms and Tool Marks FRSC 7104 Criminalistics I Professor Bensley."— Presentation transcript:
Chapter 21 – Firearms and Tool Marks FRSC 7104 Criminalistics I Professor Bensley
FRSC 7104 – Chapter 21 Objectives After studying this chapter, the student should be able to: Recognize the various types of firearms and their basic components Recognize the various types of ammunition and their uses Understand how firearms evidence is collected and analyzed Describe the basic details of tool mark comparisons and firing distance determinations
FRSC 7104 – Chapter 21 Outline I.Introduction FBI Uniform Crime Reports (2011) Murder Victims by Weapon, 2007– Total14,91614,22413,75213,16412,664 Total firearms:10,1299,5289,1998,8748,583 (68%)(67%) (68%) Handguns7,3986,8006,5016,1156,220 Rifles Shotguns Other guns Firearms, type not stated1,7051,8251,8281,9331,587 Knives or cutting instruments1,8171,8881,8361,7321,694 Blunt objects (clubs, hammers, etc.) Personal weapons (hands, fists, feet, etc.) Poison Explosives Fire Narcotics Drowning Strangulation Asphyxiation Other weapons or weapons not stated1, Pushed is included in personal weapons.
Bullet Impressions Left - A bullet fired from a conventional 6/right rifled barrel Right – 40 Caliber bullet with polygonal rifling impressions like those seen on the 40 caliber bullet
FRSC 7104 – Chapter 21 Outline 2.Caliber
Caliber Left to Right:.50 caliber down to.22 caliber
FRSC 7104 – Chapter 21 Outline 3.Gauge
FRSC 7104 – Chapter 21 Outline C.Firearm Ammunition 1.Bullets 32 S&W LONG caliber plain lead bullet 9mm LUGER caliber FEDERAL "Hydra-shok" bullet 7.62x39mm caliber armor piercing bullets
FRSC 7104 – Chapter 21 Outline 2.Propellants 3.Primers 4.Cartridge Cases 5.Shot shells Video of Firing Action in a Firearm
Plain Lead Bullet
FRSC 7104 – Chapter 21 Outline D.Forensic Examinations of Firearms 1.Class vs. Individual Characteristics Land Impressions: Left AUTO caliber FMJ bullets fired from a EAA Corp. pistol Right - 9mm LUGER caliber FMJ bullets fired from a BROWNING pistol.
General Rifling Characteristics Search CARTRIDGEMANUFACTURERTWISTL&GLANDGROOVE 9MM LUGERAA ARMS INCR MM LUGERASTRAR MM LUGERBERETTAR MM LUGERHI-POINT FIREARMSR MM LUGERINTERDYNAMICR MM LUGERLLAMAR MM LUGERMAUSERR MM LUGERSMITH & WESSONR MM LUGERSTARR MM LUGERSWD INCR mm LUGER bullet, fired from a 6/right rifled barrel, with a land width of.055mm and a groove width of.125mm. Firearm examiners will usually search with a plus or minus tolerance and the results of the search would look something like the data contained in the above table.