2. What is Internal Ballistics?
◻ Ballistics is the science of launching projectiles
using propellant or gunpowder
◻ Internal Ballistics is the science of what goes on
inside of the gun
1. Lock time, the time from sear release until the
primer is struck
2. Ignition time, the time from when the primer is
struck until the projectile starts to move
3. Barrel time, the time from when the projectile
starts to move until it exits the barrel.
3. History of Ballistics
◻ Ballistics began with the invention of the first
muzzle loading cannons in the 1200’s A.D.
◻ The first handheld guns were muzzle loading
rifles and were developed in the 1400’s
◻ The first guns were smoothbores
4. Beginning of Internal Ballistics
◻ Since the invention of the first firearms, people
have been trying to maximize:
◻ Accuracy
◻ Range
◻ Fire Rate
◻ Damage
8. Propellants and Burn Rates
◻ Fast burn rates
◻ Inconsistent
◻ unstable
◻ Slower burn rates
◻ Increased velocity
◻ Consistent
◻ Different shapes of
grains for different
surface areas
Black Powder Modern Smokeless Powder
9. Burn Rate Equation
◻ where BR is Burn Rate
◻ β and α are found empirically with experiments
◻ ζ (zeta) is the burn augmentation factor that
accounts for energy from grain fracture and
inconsistent grain burning
◻ υ is the projectile velocity
10. Bore Size
◻ A firearm, in many ways, is
like a piston engine on the
power stroke. There is a
certain amount of high-
pressure gas available, and
energy is extracted from it by
making the gas move a
piston — in this case, the
projectile is the piston
11. Bullet Size
◻ The caliber of the gun is usually the diameter of the bore
◻ Most guns are maximized for length, based on the velocity of the
normal projectile weight
◻ 120 calibers
12. Loading Density
◻ Ratio of the weight of the powder charge to the
capacity of the powder chamber
◻ Measured in grains
◻ More fully the powder charge fills the case the
more consistent and accurate the load will be
14. Barrel Length
◻ Measured from the face of the muzzle to the base of the
seated bullet
◻ Barrel length determines muzzle velocity
◻ Velocity increases with barrel length up to a certain length
dependent on bullet size and propellant
◻ Typical barrel lengths:
18-24 inches for rifles
2-8 inches for handguns
Velocity Range
Vel change
per inch
0-2000 5-10
2000-2500 10-20
2500-3000 20-30
3000-3500 30-40
