Characterization and Evaluation of Fired Projectiles
Recovered Bullets and Projectiles - Recovered bullets can be helpful to due the amount of class characteristics that can be identified
Examination - There are a number of steps that need to be taken when examining a bullet. Some of which include extensive documentation, following lab protocols, identifying patterns and overall composition of the piece of evidence
Physical Features
Manufacturer Determination
General Rifling Characteristics
Microscopic Marks
Conclusions - If any conclusion are made after an examination, it is done so through a formal written report. Any discoveries or examination notes are included
Fired Shotshell Components
Examination
Composition - Different bullets are made from certain types of materials. Some individual bullets can be made up of multiple types of materials
Jacket Type - certain types of bullets have a different type of jacket which may include a full metal jacket, semijacketed or total metal jacket
Caliber/Diameter - There are two types of diameters that can be measured: the bore diameter and the groove diameter
Properties - Some properties of a bullet include whether or not they are magnetic as well as their length
Weight - the unit used to measure the weight of a bullet is grains per pound. Different types of cartridges have certain weights
Color and Finish - The color of the bullet itself or the color of the finish typically indicate which materials were used in the production of the bullet
Characteristics - Typical characteristics of bullets include its weight, diameter, jacket type, length, color/finish, base shape, cannelures, etc.
Base Construction - Certain bullets have different base constructions which include a solid base bullet, open base, jacketed solid base, or gas check bullet
Terminology - The parts of a bullet include the tip, meplat, ogive, nose, cannelure, bearing surface, base and heel
Cataloging - A typical catalog would include two examples of a cartridge. The first example would be the intact cartridge and the second example would be a disassembled cartridge to show all its components
Identification Resources - If a proper identification can not be made, other information can help determine the caliber grouping of the bullet in question
Techniques - Some ways to get measurements include the number of visible lands and grooves, the measurements of the lands and grooves, measurements of the visible lands and grooves. The measurments should be expressed to the nearest thousanth of an inch
Equipment - Includes a stereomicroscope, calipers, micrometer, glass measuring reticule, electronic reticule, digital measuring equipment and software, MP 6 optical projector, and a machinist’s scale
Measuring Impressions - The land and grooves impressions that are left on fired bullets need to be measured
FBI GRC File Standards - Includes all the standards neeeded to make comparisons for class characteristics
Categories - general characteristics can be categorized into groups of the caliber, number of lands/grooves, direction of the twists and the land/groove impression
Damaged Bullets - Although damaged bullets are typically useless for comparison, any sort of land or groove impression that is still visible may still be measured
Reloaded and Handloaded Bullets - Due to the ways in which these bullets are loaded, the impressions that are typically left on them post firing
Effects of firing - The types of impressions that are typically left post firing include shaving, skid marks, blowby, barrel leading, and lead smaears
Bullet Design - Different type of bullets will have different types of impression (if any at all) depending on the design
Impact Damage - Depending on the extent of the damage on a bullet, the jacket may be examined or ant trace evidence will be removed and examined
Rifling Impressions - Different kinds of rifling impression include the polygonal rifling which can not be measured due to the rounded edges. Some fired bullets do not have any impresson due to the use of an incorrect size of the bullet for that firearm
Medical and Autopsy Procedures - Since medical personal can add additional markings to bullets during its removal from a patient, they need to ensure the bullets are removed without further damaging it
Shotshell Projectiles - Typically includes the shot pellets, buckshots, and shot gun slugs
Buffer Material - Typically determines from the residues left on the clothing of the victim
Wadding Material - The wadding material can reveal information like the gauge of the shotgun, the manufacturer, and/or the shot sizes
Inconsistencies - If there are any inconsistencies, that may indicate that there was a second type of ammunition
Shotshell Pellets - Determining shot size typically involves determining the average weight of the pellets
Shotgun Slugs - These are typically compared along side laboratory standards
Wadding Mterial - Examining the wadding material involves test firing a known sample that can be used to compare with the unknown
Buffer Material - Buffer material can also be compared along side laboratory standards
Dillon, H. John. “Module 10 :: Characterization and Evaluation of Fired Projectiles” Firearm Examiner Training, projects.nfstc.org/firearms/.