Various factors of internal ballistics

1. Internal
ballistics

2. What is internal ballistic
• internal ballistics is the study
of what happens within the
barrel of a weapon from the
moment the firing pin hits the
primer to the time the bullet
exit from the barrel .

3. Phenomenon of internal
ballistics
Ignition
Combustion of propellants and barrel length
Atmospheric condition like temperature etc.
Shape of the cartridge case
Heat problems and combustion of propellants
Burning of propellants and geometry of gun
powder
Pressure and its measurement

4. Ignition
• When the firing pin strikes the hammer,
the priming compound explodes with
great velocity causing jet of flames often
extremely high temperature to pass
through the flash hole into propellant
chamber .this jet of flame with a
temperature of about 2000° C ignites the
propellant which burns at high speed to
form a large volume of high pressure gas

5. Lock time Ignition time Barrel time
Ignition

6. Lock time
• Lock time is the time interval
between release of the sear and the
impact of the striker on the
percussion cap.

7. Ignition time
• Ignition time is the duration or interval
between the striking of the firing pin to
blow the ignition of the first grain of
powder.

8. Barrel time
• Barrel time is the time interval from
the passing of the trigger to the exit
of the bullet from the muzzle end.

9. Combustion of propellant
and barrel length
• Generally small barrel firearms require quick burning
powder is converted into gases, before the projectile is
pushed out of the barrel. If slow burning powder is used
in small barrel firearms ,air will be achieved of less
velocity to the projectile . In long barrel firearm , require
progressive burning powder so that powder is converted
into gases and will provides sufficient velocity to the
projectile travels through the barrel.

10. Atmospheric temperature
• The ammunition is manufactured to give the desired velocities
and pressures at a particular atmospheric temperature. If the
temperature differs only slightly at the place of the use, the
ballistic aspects are not seriously affected. If temperature
variations are substantial (e.g., in Ladakh or in Rajasthan
desert), they affect the ballistics aspects of the ammunition. In
hot places the pressures developed may be excessive and
the firearm may burst. In cold places the ammunition may
develop low velocities. Indian Ordnance Factories
manufacture most of their ammunition with a temperature
tolerance of —52°Cto72°C.It has been found that the variation
in velocities because of the temperature is about one meter
per second per degree centigrade.

11. Shape of the cartridge
case
• It has been observed that if there is an abrupt junction of
the neck and the case, the rounds develop greater
pressure (for the same quantity of powder). The
combustion is more uniform. It appears that abrupt neck
joint deflects the hot gases inward. The hot gases
quickly ignite the powder charge in every nook and
corner. Thus correct initiation and complete combustion
of the powder charge takes place inside the cartridge. It
reduces excessive heating and wear and tear of the barr

12. Heat problems and
combustion of propollents
• During the combustion of propellants, the temperature
often reaches to 3000°C. The steel barrels of the firearm
easily melt at these temperatures, if gases at this
temperature remain in the barrel for any appreciable
time. But fortunately the time for which the hot gases are
in contact with the barrel is about 0.001 second. The
repeating firearms (automatic or semi-automatic) are
eroded. more quickly. In these the barrels do not get
sufficient time between the shots to get cooled. The
erosion at high temperatures is greater.

13. •Thank you
• By Reeta pandey