Bones 22: Ballistics

What is ammunition/cartridge?

4 integrated parts of what gets fired from a firearm

what is the bullet part of the ammunition?

the part that gets shot out

What is the charge of the ammunition?

What is used to drive the bullet down the gun’s barrel

What is the most common propellant/charge?

nitrocellulose

What is the case part of the ammunition?

the enclosure of the propellant and the bullet

What is the primer part of the ammunition?

the charge igniter, propagated through percussion

What is this?

The barrel

What is this?

The muzzle

Why does a bullet spin when it comes out of the barrel?

barrel rifling grooves to increase stability

What is the caliber of a gun?

internal diameter of a gun barrel in inches or mm

Why is the bullet larger than the bore of the gun barrel?

tightness increases accuracy, making the rifling more effective and prevents the leakage of hot gases propelling the bullet

What is the difference between rifle and handgun ammunition?

Rifle ammunition has more propellant and length of the case. The case is also more likely tapered near the end

What is the purpose of full metal jacketed bullets vs semi-jacketed bullets?

FMJ goes through tissue more

Soft and hollow point deform and shred tissue

when fired into tissue, what does a bullet form?

What would an entry vs. exit wound look like for FMJ bullets vs fragmented/NJ/SJ bullets?

Fully jacketed bullets make oval entry or exit wounds

deformed/fragmented bullets make irregular holes (especially on the exit)

Name these shotgun ammunition

Birdshot- small diameter

Buckshot- larger diameter

Slug

What is the gauge of a shotgun?

Gauge number = number of lead balls that it would take to equal 1 lb.

Correlated with Size of a bore

Smaller number means a larger bore means can have more pellets within each shot

How does spread of a shotgun’s pellets change with distance?

Spread increases as range increases

How can you guess the caliber of the bullet by looking at the size of the cranium’s wound?

Average size of the entry wound tends to be just a bit larger than the caliber of the bullet

What is the correlation of the effect on bone with energy?

Effect of bullet on bone is proportional to kinetic energy

KE=1/2mv²

• This is why speed is most important factor for the effect of the bone

How do you get more energy in a bullet?

More propellant

• found in rifle ammunition

Due to greater energy, what are you more likely to see as a result?

• Exit wounds

• Radiating and concentric Fractures

• Highly comminuted shattering

Which is the entry and exit wound?

Is this high or low velocity?

Entry on the left, exit on the right

• low velocity

Is this an entry or exit wound?

Is this high or low velocity?

Exit wound

• High velocity