Forensic Firearms, Toolmarks, and Serial Number Restoration

Comprehensive fill-in-the-blank practice flashcards covering forensic firearm identification, ammunition and toolmark analysis, and serial number restoration.

In 1925, the comparison microscope shown in the diagram was developed by __________.

Philip Gravelle

name the component that differs a revolver from a pistol

cylinder

name the components that differ the pistol from the revolver

safety, extractor, slide, ejector

what activates the firing pin in a revolver

hammer

While often termed forensic ballistics, ballistics is accurately defined as the physics study of an object in __________.

flight

According to voluntarily reported FBI homicide data over a 5-year period, __________ percent of homicides were committed using firearms.

76%

In a __________ revolver, the hammer can be cocked either by hand or automatically by pulling the trigger.

double-action

The percussion-sensitive material inside a firearm primer cup typically contains lead styphnate, antimony sulfide, barium nitrate, and __________.

tetracene

On the discharged cartridge case shown in the image, feature B indicates an __________ mark, which is only created if the casing is expelled from the firearm.

ejection

Shotgun barrel size is measured in gauge, which equals the number of lead balls of the barrel's diameter that weigh __________ pound(s).

one

Numerals, letters, or symbols stamped into the head of a cartridge case or shotshell to identify manufacturer and caliber are called a __________.

headstamp

A knurled or plain groove on a bullet or cartridge case that provides a crimping surface and holds lubricant is called a __________.

cannelure

__________ rifling produces lands and grooves with a rounded profile and smooth transitions, and is produced using hammer forging.

Polygonal

When a firearm is recovered from water at a scene, safety guidelines dictate packaging it in a container filled with __________.

the same water

The four General Rifling Characteristics (GRC) of a firearm barrel are caliber, direction of twist, width of lands and grooves, and the __________ of lands and grooves.

number

The caliber of a rifled firearm barrel is defined as the bore diameter measured from __________.

land to land

Microscopic imperfections on the interior barrel surface that impart unique individual impressions onto a fired bullet are called striations or __________.

striae

The three general patterns of breechface marks transferred to cartridge cases during firing are circular, arched, and __________.

parallel

The hooked metal component designed to pull a fired cartridge case from the chamber is the __________.

extractor

The three major characteristic elements identified in primer gunshot residue (GSR) are lead, barium, and __________.

antimony

In the Modified Griess Test for gunshot residue visualization, nitrite residues appear as __________ dots on treated photographic paper.

orange

When applying sodium rhodizonate solution to detect lead residues around a bullet entrance hole, the residues turn pink and then __________.

purplish-blue

The ring of lead, primer material, and carbon transferred directly onto the outermost target surface around an entrance hole is known as bullet __________.

wipe

According to the choke diagram, a __________ choke produces the tightest constriction and maintains a 40-inch spread out to approximately 40 yards.

Full

In forensic identification, a tool is considered the __________ of two objects that leaves a mark in the other when brought into contact.

harder

The tool action in which two blades on adjacent planes pass by each other to cut material, such as in scissors or tin snips, is called __________.

shearing

Locking pliers, commonly known by the trade name Vise Grips, are classified under the __________ tool action category.

gripping

Diagonal cutting pliers cut wire using opposed jaws in a pinching action, which leaves a characteristic “__________” shape on the cut surface.

roof top

Lineman's pliers feature serrated teeth at the front of the jaws for gripping and cutting __________ at the rear of the jaws.

blades

The waste material produced during drilling that is evacuated by the flutes of a drill bit is known as __________.

swarf

An impressed toolmark, also called a compression mark, produces a __________ image of the tool surface.

mirror

A toolmark formed when a tool slides or scrapes across an object under pressure is classified as a __________ toolmark.

striated

Shown in the photograph, __________ is a silicone-based casting material widely used to recover toolmarks from immovable surfaces.

Mikrosil

When generating test toolmarks for comparative examination, examiners typically use a soft metal such as __________ to avoid altering or damaging the tool's edge.

lead

The first step in comparing striated toolmarks is establishing the correspondence of __________ characteristics.

class

A unique identifier applied to manufactured items like electronics, vehicles, and firearms is a __________.

serial number

Unlike dot matrix engraving, serial numbers engraved with a laser are shallow and feature a distinct __________ appearance on their edges.

burned

When a serial number is applied to metal using a hard die stamp, the impression remains permanently due to __________ deformation.

plastic

In stamped steel, the compressed, strained crystal lattice area below the surface stamp mark can extend for approximately __________ times the depth of the stamp.

6

Cold working refers to shaping metal below its __________ temperature, which increases hardness but reduces resistance to chemical oxidation.

recrystallization

In chemical restoration etching of steel, copper salts promote the oxidation of iron, where iron dissolves according to the half-reaction: $\text{Fe} \rightarrow \text{Fe}^{2+} + \text{\_\_\_\_\_\_\_\_\_\_}$.

$$2e^-$$

As illustrated in the diagram, acid-etched serial numbers appear dark under direct light because the rough etched metal causes __________ reflection.

diffuse

The first procedural step in restoring an obliterated serial number is to polish the metal surface with grinding tools or sandpaper using progressively __________ grits.

finer

During acid etching of an obliterated serial number, the active reaction of acid with metal is indicated by the formation of __________ gas bubbles.

hydrogen

In the ATV engine case study, the obliterated vehicle identification number was successfully recovered after sanding by applying Acidic __________ Chloride.

Ferric

In the shotgun case study where the serial number had been ground off, applying 25% __________ acid successfully revealed the serial number H924850.

Nitric