CSI Firearms and Ballistics

Week 11

.22 caliber is cheap (ammunition, gun size) & small & easy to use = criminal’s weapon of choice

  • pinball machine

    • unpredictable

  • bleeding out

.9mm = bigger, more damage

  • Straight through

Ballistics: study of a projectile in motion

  • something in flight

Internal: what’s happening inside the gun.

  • the study relating to the transition of chemical energy to kinetic energy within the barrel of a firearm and the motion of the projectile as it moves through the barrel.

  • Cartridges (bullets) go in the magazine (upper handle), then the cartridge casings (gold things) are the propellants and they’re what drop when you shoot. Goes up a ramp.

    • Cartridges go: primer, projectile, propellant

      • Ex (semi-automatic):

        • operability of the firearm

External: what’s happening outside the gun/what happens after the bullet leaves the gun.

  • gunshot residue

    • Griess Test

  • Lead, Barium, Antimony

    • up to 6 hours on hands if not washed

  • Burn.

  • IR photography for GSR

Terminal: when it strikes the object.

  • Projectile deign and its deformations

  • mass

  • velocity

  • KE energy on impact; KE lost on the target

PENETRATED: it hit the thing but didn’t go all the way through

PERFORATED: went through.

Ricochet: has to come in at an acute angle (10 - 15 degrees)

  • never penetrates or perforates

Pinch Point: when it turns really fast; initial contact with the surface

                                        Inverse Sin (width/length)

Chisum Trails: Elongated ricochet mark on unyielding surfaces.

Cartridge Case Comparison:

  • Ejector, which is the mechanism in a firearm that throws the cartridge or fired case from the firearm.

  • Extractor, which is the mechanism in a firearm by which a cartridge of a fired case is withdrawn from the firing chamber.

Firearms Examination: operability testing, GSR distancing and analysis, toolmark analysis

Firearms Identification: through the fired bullets and cartridges (comparison)

Hand guns: pistols, revolvers, etc.

Long arms: rifles, shotguns, etc.

Rifling: the inner surface of the barrel of a gun leaves its markings on a bullet passing through it. Lands and Grooves + the striations on each——-Twisting left or right:

  • Land = raised (in gun barrel), flat (in projectile)

  • Groove = flat (in barrel), raised (in projective)

    • Unique identifiers

THEY ARE NOT REALLY IN METRIC UNITS (except 9mm)

The gauge is responsible for ejecting the spent shell casing after its been fired


Backspatter: In a contact shot to a victim there is often blood found within the barrel of the handgun.

Ammunition

Shotguns: smooth barrel

  • (Buckshot) 8-9 BALLS

  • (Buckshot) 8-9 mm

Shotgun Shell:

            Wadding comes out with the balls; will hit someone or something but without power.

                                    bc it’s plastic/doesn’t have mass to do any damage

“I obtained latent print (RR-1) from the crime scene”

  • size

  • what you see

  • what you’re going to pass onto the detectives

Must have PHOTOS OF THE SNEAKER for examination

All the math has to be done before the trajectory rods go in

  • road-mapping = mini crimescene

Integrated Ballistic Identification System (IBIS) — owners of guns and bullets and shii

National Integrated Ballistic Information Network (NIBIN) — network used to talk between state and federal, etc.