Forensics Ballistics & Firearms WebQuest

Investigate forensic ballistics & firearms ID! Learn about bullet analysis, GSR, and toolmarks.

Click the link below.Once you get to the website on LEFT hand side of page, click “Firearms Identification”The answers to the following questions can be found by going through the menu of pages listed on the left.Pay attention to the headings, the pages match these headings – click “next” to proceed through. Firearms and Ballistics WebQuest Link Click the INTRODUCTION Heading The identification of fired bullets, cartridge cases or other ammunition components as having been fired from a specific firearm is the area known as firearms identification . It is often incorrectly referred to as ballistics. What type of evidence is usually processed at the firearms division of the forensics lab? True or False.Once the evidence is analyzed by the firearms technician, he is relieved of further responsibilities. True False Click the FUNDAMENTALS OF FIREARMS ID Heading What two characteristics are used when identifying firearms? True or False.Firearms have to be recovered within 2 weeks for correct identification. True False Eightypercent of firearms produce a “mechanical fingerprint” on the bullets and cartridges. The preliminary examination of firearm examination involves the examination of class characteristics Class characteristics can be defined as Examples of firearm class characteristics are After similar class characteristics are determined, the final stage to find a “match” is called individual characteristics Click the BULLET IDENTIFICATION Heading Name the two class characteristics of bullets Scratches or microscopic striations are transferred from the gun to the bullet. The rifling impressions look very similar to Glass shatter Spiderwebs Bar codes Bullseye These patterns can be unique which means different for each bullet. What are Standard bullets fired into Clay Cardboard Stones Water tank Evidence and standard bullets are compared on comparison microscope comparison macroscope Stereo Microscope Polarizing Microscope Questioned bullets are usually damaged or even broken into fragments. If a firearm IS NOT recovered what may firearm examiners use to examine the collected bullets? Click on the CALIBER Heading Caliber of a bullet is the diameter of a bullet in hundredths of an inch In Europe, caliber is measured using the metric system. Bullets are contained in a Socket Cartridge Barrel Muzzle A cartridge is a single unit of ammunition consisting of the cartridge case, primer, and propellant with or without one or more projectiles. What do cartridge designations tell you? Explain how bullets vary? Explain why finding a questioned bullet doesn’t tell you what cartridge the bullet came from. Click on the RIFLING Heading. What is rifling? What does rifling do? Name three main basic machining processes manufacturers use to form rifling in gun barrel. Which rifling process does Glock use? Electrochemical Rifling Button Rifling Hammer Forged Rifling Broach Rifling Which method does not require consumable tools? Electrochemical Rifling Button Rifling Hammer Forged Rifling Broach Rifling How does polygonal rifling differ from traditional rifling? Click on the RIFLING IMPRESSIONS Heading A bullet is _ size as the barrel from which is it fired. Smaller Larger Same Size How is bore diameter measured? How do you determine rifling pattern and direction of rifling? Explain what can be different about 2 bullets, both fired from a 6 rifled barrel? What is rate of twist? What is pitch? Click on the GENERAL RIFLING CHARACTERSTICS (GRC) Heading What are general rifling characteristics? What is the general tolerance firearm examiners will usually search for the width of lands and grooves? Who maintains a database of rifling data? Click on the CARTRIDGE CASE IDENTIFICATION Heading True or False.The cartridge does have to be fired for these marks to be transferred. True False Striation action marks are: Impressed action marks are: Click on the STRIATION ACTION MARKS Heading Striation action marks are produced on cartridge cases. How are chamber marks formed? What is the difference between an extractor and an ejector? Click on the IMPRESSED ACTION MARKS Heading What causes impressed action marks? The two most common impressed action marks are True or False.Firing pin impressions are found only on spent cartridges True False What is recoil Where is the breech face found in a firearm? What are some different types of breech marks? ON THE LEFT HAND SIDE OF THE PAGE-Click on HOME then CLICK ON DISTANCE DETERMINATION The evidence needed for a distance determination will be on the _ side. Entrance Exit Parallel Perpendicular Click on the GUNSHOT RESIDUE Heading What information can be learned about a crime by determining the muzzle-to-target distance? Describe the residue pattern when a bullet is expelled from the barrel. How does the residue pattern change as the distance changes? Describe the difference in pattern between low velocity and high velocity ammunition. How far can gunshot residue (GSR) travel? How does the distance correlate with the diameter of GSR? What are the ingredients of gunpowder? What is the composition of its residue? What is source of lead residue In what forms will you find lead residue? Click on the GUNSHOT RESIDUE EXAMINATIONS Heading How is clothing packaged to preserve the evidence? Describe in detail the steps you would take if you were asked to examine a shirt for GSR? Describe how the Modified Greiss Test detects GSR. Click on the GUNSHOT RESIDUE STANDARDS heading What are GSR standards and witness panels? Click on the GUNSHOT RESIDUE TEST RESULTS Heading What are the possible results an examiner might report?