History of Firearms

• Firearms and ballistics are key topics in forensic science

Ancient History of Firearms

• Firearm history starts with gunpowder invention in 8th century China
• Gunpowder consists of sulfur, charcoal, and saltpeter
• The gunpowder formula was first mentioned in 808 AD in China
• Gunpowder's first military use was in 904 AD
• The fire lance, a primitive rocket, was the first ancient projectile, used in 1132 AD.
• Invading Mongols spread gunpowder from the Middle East to Europe and the rest of the World.
• Cannons were first used in the Battle of Ain Jalut in 1260 AD
• Gunpowder production in London's Tower began by 1346 AD

Early Firearm Evolution

• The matchlock was the initial historical firearm
• Gunpowder was ignited with burning rope in matchlocks tied to the trigger
• Matchlocks enabled shooters to independently ignite gunpowder
• The flintlock firearm uses flint-striking to ignite gunpowder
• The flintlock prototype was in use by 1547 AD in Europe
• Countries that could afford them chose flintlocks over matchlocks
• By the 18th century, most European militaries used flintlocks

Modern Firearm Innovations

• Mid-19th-century breechloaders revolutionized firearms
• Bullets were loaded in the back of the barrel, not the front
• Most firearms are loaded by breech-loading today
• Mortars and a few grenade launchers still use muzzleloaders
• The Colt Paterson, the first repeating revolver, came out in 1836
• The Colt Paterson could shoot 5 bullets in repetition after cocking
• The Gatlin gun, an early machine gun, was invented in 1861
• The Gatlin gun had 6-10 barrels and needed 4 people to operate
• It could be fired by one person and used handgun cartridges
• The first submachine gun appeared in 1918 during WWI

Rates of Fire Classification

• Firearms are classified by their firing rate: manual, semi-automatic, or automatic
• Manual firearms require the shooter to manually insert a round into the chamber
• Semi-automatic guns require the shooter to pull the trigger for each shot fired
• Shooter can fire continuously as long as the trigger is held/until out of ammo with automatic firearms
• The ATF regulates automatic weapon sales, requiring a revenue stamp and background check
• Bump Stocks modify semi-automatic guns for rapid firing, faster than a human can
• Bump stocks are illegal federally after the Las Vegas Mass Shooting

Firearm Types

• A firearm is any device made to expel a projectile via explosion, burning substance, or convertible device
• There are five types: handgun, shotgun, rifle, submachine gun, machine gun

Handguns

• A handgun is made to be fired with one hand
• The two main types of handguns are semi-automatic pistols and revolvers
• Semi-automatic pistols are repeating firearms needing a separate trigger pull for each shot
• Semi-automatic pistols use the energy of discharge to perform part of the operating/firing cycle
• Revolvers have single and double actions
• Single action needs manual cocking before trigger release
• Double action cocks and releases the hammer with a single trigger pull

Rifles

• Rifles are long-barreled firearms for accurate shooting
• Bolt action, slide action, and lever action
• Bolt Action Rifles load rounds by bolt reciprocation
• Slide Action: pumping the forearm manually pumps the barrel and are knowns as Pump Action
• Lever Action cycles the breech via an external lever generally below the receiver

Shotguns

• Shotguns are long-barreled firearms designed to shoot shotshells or slugs
• Several types of action exists: break, pump, lever, bolt, revolver, semi-automatic
• Most shotguns have smooth barrels without rifling

Machine Guns and Submachine Guns

• Machine guns are designed to fire rifle cartridges as long as the trigger is held down
• Automatic rifles are designed for short bursts but Machine guns are designed for continuous firepower.
• Machine guns are mainly used in today's usage as infantry weapons
• Submachine guns fire handgun cartridges when held up, these types of guns were made for trench warfare during WWI.
• This type of gun is not popular due to accuracy.

Basic Parts of a Pistol

• The barrel is a long metal tube that extends from the frame, and directs the bullet during shooting
• The grip is the portion of a handgun used to hold the firearm
• The muzzle is the front end of the barrel where fired projectiles exit
• The magazine is where the ammunition sit and loads into the chamber
• A sight helps a person aim a firearm
• The trigger fires the cartridge

Ammunition Details

• Ammunition are bullets fired from a firearm
• Bullets have different shapes, sizes, calibers, and designed to be fired from specific firearm types
• Caliber is the diameter of the gun barrel (inches or millimeters)
• Bullet headstamps have numerals, letters and symbols stamped on its head that shows what the cartridge case or the shotshell identify manufacturer/caliber

Bullet Comparisons

• Bullets are recovered from crime scenes or autopsy when firearms are used in crimes
• Striations are markings left on bullets by the machining/rifling in the barrel and used to compare rifles/handguns
• The first fired bullet step to compare it examines the land and groove width
• Land is ridges or lines
• Groove is spaces between lands

Rifling Methods and Uniqueness

• Factories mass-produce firearms, so barrels are similar in their firearm type and land/groove caliber as the manufacturer
• A .32 caliber Smith & Wesson revolver has 5 lands and right-twisting grooves
• Forensic technicians can determine the brand of weapons using the rifling process of lands and grooves but CANNOT find an individual weapon
• Striations are unique to each barrel and can identify a bullet fired from an exact, individual weapon
• Imperfections result in said conditions and are not the same for firearms made by the same manufacturer in the same factory

Cartridge Components

• A pre-assembled firearm round is in the cartridge packaging a bullet
• Cartridges consist of bullet, cartridge case, gunpowder, rim, and primer
• The cartridge case holds all parts together
• The rim allows the firearm to grip the casing for removing it once fired
• The primer ignites the gundpowder

Cartridge Case Examination

• The firing pin strikes the gun's primer when the trigger is pulled, which ignites the gunpowder
• Explosion gases propel the bullet forward and results in cartridge case goes backwards
• The cartridge or shell case is marked with unique and individual markings inside the gun chamber
• Markings appear from firing pin, the elector and extractor itself, and the marking on the chamber face
• Test firings can re reproduce if tests from same firearm are produced in similar patterns
• Comparing the unknown shell casing is achieved from testing to compare from crime scene, and then compare

NIBIN

• In 1999, the ATF and FBI created the National Integrated Ballistic Information Network (NIBIN)
• Before, each agency had their own incompatible systems
• NIBIN agencies can now upload crime scene bullet and cartridge photos and test-fired samples from known weapons
• This is a screening tool needing a ballistic expert to compare samples via microscope -NIBIN narrows possibilities for ballistic experts to see if its the same weapon being used in crime scenes

Ballistics Career Details

• Ballistics, or firearms examining, involves bullet projectiles and firearms.
• A ballistics expert examines/identifies firearms and ammunitions, upload evidence to testing sights (NIBIN) and testifes to court regarding criminal findings
• To be a firearms examiner, forensics degree is needed
• Average yearly salary in the US for a firearms examiner $52,234

Deciphering Distances

• Gunshot wounds reveal distances that the gun was fired
• Contact wounds have burns and an abrasion ring
• Can be suicide or execution-style killing
• Intermediate wounds of black specks are from regular ammunition: Up to 2 feet
• Distant wounds, more than 2 feet away, have bullet holes with small dark rings
• Distant wounds are usually linked to homicide
• Clothing can change the appearance of specks and lead.

Entrance vs. Exit Wounds

• Entrance and exit wounds are impacted from the distance
• Entrance Wounds compared to exit wounds are smaller, symmetrical, have star shape and close spec patterns
• Exit Wounds are similar to entrances in Characteristics but are more irregular and without abrasions

Gunshot Residue Analysis

• Gunshot residue may be found on victims if distance from firearm isn't within 3 feet
• If a gun is held less than 3 feet away, there is a high likelihood of the gunman having residue on their hands
• Gunshot Residue Tests
• The gun needs to be photographed using an infrared lens
• A Griess Test identifies nitrites: press paper onto clothes and iron to change orange and a color if present
• Further chemical tests are made for lead
• A Primer Gun Test to compose is for lead, antamony and Barium.
• This involves for handlers and swabbing the hands within the time period

Crime Scene Processing Protocols

• Important considerations:
• If it securing to process, Do not move if scene is secured
• Thoroughly photograph firearm with close ups of weapons
• Prior to conducting handling, use process for touch
• If packaging, if removing, do not take the objects, use object with bullet
• Store ammunition individually