jimtrue.com : school : CJT1110 : CH10: Firearms
Posted by Jim True on March 3, 2003 6:00 AM. Last Updated October 22, 2006 9:23 PM
Disclaimer for all material noted here is at the bottom of this web page.
Definition of a FireArm: A device which fires a projectile or projectiles as a result of an explosion or a propellant charge.
Different Types of Weapons (Firearms)
1. Rifled weapon (not a longarm) - interior of the barrell with lands and grooves, twisted spiral within the barrell to force the bullet to spin and aerodynamically travel straighter. Straighter trajectory; better aim.
Bullet is just a tad larger than the caliber (.45 caliber round is .45/inches, barrell is .444). When fired the bullet is pushed slightly into the grooves.
2. Smooth bore - not spinning so it will tumble.
Once a projectile hits something it will NOT travel in a straight line. The trajectory along a bone, along a wall, etc. will tumble and do even more damage.
Caliber is measured from the LANDS, not the groove. Actual caliber of the bullet fits somewhere between the lands and the grooves. The lands will make the striations on the bullet itself.
Two Classifications of Weapons
1. Handguns (something you hold in your hands)
a. Different types of Handguns:
1. Revolver - Chamber that spins (revolves) (4 to 20 shots), rotates up to the barrel, hammer falls and.
Two types:
a. Single Action - Hammer has to be cocked back before you can pull the trigger. Fanning would be pulling the hammer back and shoot the trigger at the same time.
b. Double Action - as you pull the trigger, the hammer automatically cocks and the trigger pull all the way back makes the hammer go back. (two actions from one trigger pull).
2. Pistol - automatically reloads itself from the ammunition clip. Outside slide moves back and loads the round.
Two Types:
a. Single Action - have to cock the hammer in order to pull the trigger and have the hammer release.
b. Double Action - as you pull the trigger, hammer automatically cocks and shoots.
Casings at the scene, automatic ammunition.
Difference: Semi-Automatic & Automatic
Mostly applies to long guns (though some does applies to handguns).
Everything described so far is semi-automatic. Have to Pull the trigger to make it shoot again.
Automatic - you pull the trigger and it shoots consistently until you stop pulling the trigger. or FULL automatic. Casings all over the place, usually in a semi-circle.
MOST revolvers and pistols have rifled barrels to make them fly straighter and smoother.
Double barrel, four barrel
2. Shoulder Arms or Long Guns (rifle or a shotgun) (Sawed off shotgun is a shoulder arm that has been cut).
(all heard it called a rifle, a rifle has a rifled barrel).
Rifles -
a. semi-automatic,
b. full automatic,
c. Pump or slide action (doing the action of the semi-automatic)
d. Lever action
e. Bolt action - the most accurate long gun you can get. No action for the casing coming back, the bolt locks the ammo perfectly in place so it cannot move. Snipers
f. Single Shot Action - shotgun or rifle, shoot, does one shot, barrel breaks from the top, drop one round up, clicks into place and shoots.
Double-barrel (side by side, or over and under)
Shot Guns - Difference not rifled, smooth bore and Shotgun shoots different ammunition
three different types: birdshot (small bb's), buckshot (bigger than birdshot), and slugs (grooves in the slug to make it aerodynamically fly) (Varmint, bird round and snake rounds for a handgun)
[ Dragon breath, small particles of magnesium that bursts into flame as it shoots out... Street sweeper, round canister with a dozen rounds of dragon breaths ]
Ammunition - Casings and rounds
Bullet/Live Round - unfired ammunition [the Entire thing is called a bullet or live round]
Casing
Projectile
Primer
gunpowder
firing pin
Once it is fired (when flying, projectile)
Once it hits something, it is a spent projectile
Once casing is fired, spent casing
Example: Spent Casing on the floor, spent projectile in the wall, subject appeared to be shot through and through.
BOOK often calls it a Bullet.
Caliber, 100th's of inches .22 caliber, .22 inches, .45 caliber, .45 inches
9mm handguns (.356 caliber)
Shotguns are 'gauges' - except for the 410 gauge shotgun, size of the round or bigness of the barrel, smaller the number the bigger the barrel. GAUGE Refers to the caliber of the shotgun, number of leadballs inside the round that will make up a pound in the given bore of the weapon.
50 caliber, .50 of a inch
EXAMPLE: Live shotgun shell (whole thing is a shell), spent shotgun shell is the casing.
Accelerator round - 100 grain is the regular projectile, rubber or hard plastic around a smaller grain projectile. Less lead, same gun powder. Raising the velocity of the round. Explodes due to running at great speed.
Hollow-round
Armor-piercing (solid steel, pointing projectile) Regular projectile is lead (soft metal).
Comparison Microscope, two microscopes that come together in one plain (striations)
GSR (Gun shot Residue): testing in the book, nitric acid not being used that much anymore. If I fired a handgun in this room, everyone would have residue (enclosed space). Most cases, especially suicides.
* 3 elements: lead, barium, and antimony.
* Most unique in everyday life: antimony
Primer residue occasionally follow the projectile out and be on the target.
Wash your hands and the GSR is gone. (or wipe).
Powder burn is different from GSR.
more than likely on the tops of the hands.
No more than 6 hours or residue will be lost.
FIRE ARMS:
Handguns & Rifles
Contact
Mid-range
Distant
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