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 Lab: Understanding BulletsIntroductionBullets are not simply one size ?ts all. They come in all different shapes, sizes and weights depending upon the gun they are to be used in as well as the type of game being shot.Concepts Bullet shapes Bullet materials Bullet masses/grains Firing pin markingsBackgroundBullets come in many different shapes and sizes. The bullet itself is the projectile located at the front end of the cartridge. They are traditionally made of lead and lead alloys. They may also be covered by a jacket of a harder metal. When the nose of the bullet is covered it is called a full metal jacket, hard point or ball ammunition. If the lead is exposed at the tip of the bullet it is called a jacketed soft point. The most common metals used as jacket material are copper, gilding metal or steel. Bullets are measured in units called grains. In this lab, you will be converting bullet masses in grams to grains. One gram is equivalent to 15.43 grains. For example, a bullet that weighs 3.89 grams would be approximately 60 grains. (so, mass x 15.43 = grains)Bullets vary in design depending upon their intended purpose. Bullets for hunting often have a soft or hollow point. This type of bullet is designed to expand on impact using the majority of the energy on the target. Conversely, target bullets often have reduced expansion making them inappropriate for hunting most game. In general, the heavier the bullet the more power it carries. For this lab, you will view an introductory video, observe images, determine calibers, note firing pin differences, and view a video that helps you to be able to calculate grams to grains, determine material types and bullet types:Part I: Bullet Caliber ComparisonsOpen the folder titled “Bullet Caliber Comparisons”. Observe the images of the various replica bullets (2 per bullet type) and record their diameter measurements. **Using the calipers, be sure and note from the Instructional Video how to read them correctly!Observe and record the measurement for the Crime Scene bullet and attempt to match the caliber of bullet that most likely matches the Crime Scene bullet.Table 1: Bullet Caliber Comparisons Caliper Measurements.22 Caliber.380 cal9mm.40 cal.45 calCrime SceneWhich bullet caliber is the Crime Scene bullet? ____________________________Part II: Firing Pin ObservationsYou will attempt to identify a suspect from the firing pin photographs of 4 different bullets.Open the folder titled “Bullet Firing Pin Comparisons”.There are four labeled bullets to compare: Suspect 1, Suspect 2, Suspect 3 and Crime Scene.Observe each one CAREFULLY. Record observations/characteristics in your table. You must have at least 3-4 items for each bullet.Attempt to match the Crime Scene to one of the suspect bullets.Table 2: Firing Pin ComparisonsSuspect 1Suspect 2Suspect 3Crime SceneWhich bullet most matches the Crime Scene bullet? What are it’s identifying features?Part III: Bullet Composition, Projectile Type and WeightYou will observe 7 differently labeled bullet projectiles (Suspects 1-7) and determine a suspect bullet from the evidence presented. Open the video titled: Bullet Composition, ProjectileTypes and Weight. Record the colors, widths and apparent metals, masses and type of projectile for each projectile shown. **A projectile CAN BE more than one type-a combo of two for example.Calculate the grains of each bullet projectile and record in the table.Using the provided information for the Crime Scene projectile provided in your table, attempt to identify the suspect bullet.Table 3: Bullet Composition, Projectile Type and WeightCharacteristicSuspect 1Suspect 2Suspect 3Suspect 4Suspect 5Suspect 6Suspect 7Crime SceneMaterialCopper/leadProjectile ShapeJacketedSize, mmMassGrains124.98Of the bullets provided, which of the suspect bullets appear to match the Crime Scene bullet? Provide your evidence in your responsePart IV: Striation Evidence.You will observe and compare several paired bullet close ups to determine if their striations are a match.Remember: The markings must appear to match in nearly all locations, side by side.Open the folder: Bullet Striations.In your table, under the numbered pairs you will simply mark “match” or “no match”.Table 4: StriationsBullet PairingsMatch or No MatchStriation #1Striation #2Striation #3Striation #4Striation #5Striation #6Striation #7Striation #8Provide a summary of at least 3 sentences explaining what you learned about bullets by completing this lab. Include how forensic scientists would use this type of information in a case. ................
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