working of muzzle and buellt

1. BallisticsBallistics
YouTube - Bullets in Slowmo

2. BallisticsBallistics
The study of Ballistics involves the:
• Comparison of bullets and cartridge cases.
• Knowledge of all types of weapons.
• Restoration of serial numbers.
• Detection of gunpowder residue.
• Estimation of muzzle to target distance.

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Comparison of Bullets and Cartridge Cases
• Guns have two basic categories:
Hand Guns
Colt .45 Automatic 1911 A1 Pistol
Rifles
.30 Caliber M1 Rifle

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• In addition, guns can be “rifled” or “smooth bored” .

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What is “rifling” and why is it necessary?
• Rifling is the machining of “lands” and “grooves” to the inside
of the gun barrel.
• These cause the bullet to spin as it exits the gun barrel giving
it stability and increased accuracy.
• Certain dimensions of this machining process give us the
“caliber” which we are so familiar with.

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• Bore – Is the distance from land to land.
• Lands – Is the area of the barrel not machined out when
rifling.
• Grooves – Is the spiral cut out of the barrel, “rifling”.
• Caliber – Is the distance between lands, inches or mm.

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• What type of evidence is Bore, # of Land and Grooves, and
Caliber? Class or Individual.
Answer: Class
Remember Class evidence is associated with a
particular group. There are plenty of 9 mm Glock
hand guns floating around.
• Can this particular 9 mm Glock hand gun become Individualized?
Answer: Yes
• After repeated firing the land and grooves become “marked” as
the bullet travels in the barrel.

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• These marking leave “striations” on bullets as they exit the
barrel.
• Investigators can match bullets with specific guns by
comparing these striations.
• It’s these striations which make each gun individualized.
We can then say a particular bullet came from a specific gun.

9. BallisticsBallistics
• How do investigators get bullets for comparison?
• Ballistic Gel YouTube - Ballistic Gelatin
• Water Tank YouTube - PHY NYA Gun bullet in water tank
• Bullets are compared and investigators can determine if a
bullet was shot by a particular gun.

10. BallisticsBallistics
• Can bullet casings be compared and linked to a specific gun?
Answer: Yes
• Just as the inside of a barrel leaves individual markings on
bullets, the firing pin will leave individual markings on the
cartridge.
• In each case, respectively, the bullets were fired by the same
gun.

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• Can investigators recover serial numbers from firearms?
Answer: Of course they can.
• By applying certain acids onto gun surface where the serial
number has been “erased” or scratched away, serial
numbers become visible again.

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• Can Gunshot Residue (GSR) provide investigators with
valuable information?
Answer: Do I need to answer this?.
O.K. Yes.
YouTube - Gun shot so slow you can see the bullet
• GunShot Residue is gun powder that does not burn when
the bullet is fired.

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• Gunshot Residue is ejected forward and backward, so the
person firing the gun will have traces of the residue on
his/her hand.
• This residue is easily detected and analyzed.
• Gunshot Residue can provide information about the muzzle
to target distance.

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• Because GSR leaves the muzzle in the shape of a cone,
the diameter of the GSR left can give an indication of muzzle
to target distance.
Point Blank 3” 9”
15” 21”

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Bullet Trajectory and Path
• Since bullets obey the laws of physics it is easy to determine
their origin and distance traveled.
• This can be done by using dowels or lasers.