Ballistics

Myth and Mechanisms of Firearm Injuries : 

Myth and Mechanisms of Firearm Injuries Dr. Joel Turner, CCFP, FRCP 3 McGill University January 12, 2000

Slide 2: 

Myths and Mechanisms of Firearm Injuries

Slide 3: 

Myths and Mechanisms of Firearm Injuries "A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed” 2d Amendment to the U.S. Constitution

Slide 4: 

Myths and Mechanisms of Firearm Injuries

Slide 5: 

Myths and Mechanisms of Firearm Injuries

Slide 6: 

Myths and Mechanisms of Firearm Injuries

Slide 7: 

Myths and Mechanisms of Firearm Injuries Objectives: 1. Epidemiology of Firearm-related injuries/deaths 2. Basic anatomy and terminology 3. Ballistics of firearms 4. Role of the EP

Slide 8: 

Myths and Mechanisms of Firearm Injuries 1. Epidemiology/Statistics Firearm death rate (per 100,000) for young males in 12 selected countries (Center for Disease Control. Births & Death, 1995)

Slide 9: 

Myths and Mechanisms of Firearm Injuries In 1997, -68% of all homicides caused by gun 92% among young blacks 86% of all suicides caused by gun Number of non-fatal GSW ranges from 140,000 to 200,000 / year 17,000 / year are treated in ED’s for unintentional GSW Just the facts…. Voelker R. JAMA, 1995 Hayert, et al. Natl Vital Stat Reports, 1999 Sinauer, et al. JAMA, 1996

Slide 10: 

Myths and Mechanisms of Firearm Injuries Firearms Deaths (per 100,000) by Mode of Death for Children <15 Years of Age - Top 10 Countries C.D.C. Rates of Homicide, Suicide, and firearm- Related death among children. MMWR, 1997 -Firearms are the 2nd leading cause of death of children in the U.S.  Number 1 cause of death in young blacks

Slide 11: 

Myths and Mechanisms of Firearm Injuries Canadian numbers… United States Canada (Hurg K, Firearm Statistics. Dept of Justice, March, 1999)

Slide 12: 

Myths and Mechanisms of Firearm Injuries Canadian numbers… (Canadian Firearm Centre- Statistics Canada)

Slide 13: 

Myths and Mechanisms of Firearm Injuries Canadian numbers… (Canadian Firearm Centre – Angus Reid Group, May 1998)

Slide 14: 

Myths and Mechanisms of Firearm Injuries Canadian numbers… (Canadian Firearm Centre- Statistics Canada. Homicide Survey, 1997)

Slide 15: 

Myths and Mechanisms of Firearm Injuries 1989-1995: 9,995 people shot in Washington State -29%  ED care only -29%  Admitted to hospital & survived -42%  died Hospital Visits and admissions 1988-1996: average 1,217 admissions/year Canada: Quebec: 1988-1996: average 287 admissions/year (23.6%) 43.6% - firearm accidents 28.2% - self-inflicted 22.0% - inflicted by others (Cummings, et al. Annals of Emergency Medicine, 1998) (Canadian Institute for Health Information)

Slide 16: 

Myths and Mechanisms of Firearm Injuries 2. Terminology & Anatomy of Firearms A. The Gun:

Slide 17: 

Myths and Mechanisms of Firearm Injuries Action Chamber Barrel Rifling Bore Caliber Muzzle Hammer Magazine (Clip) Anatomy of the Gun

Slide 18: 

Myths and Mechanisms of Firearm Injuries The Guns Handguns Single shot weapons (target pistol) Derringer Revolver Semi-automatic pistol 2. Rifles 3. Shotguns 4. Fully automatic

Slide 19: 

Myths and Mechanisms of Firearm Injuries The derringer

Slide 20: 

Myths and Mechanisms of Firearm Injuries The Revolver

Slide 21: 

Myths and Mechanisms of Firearm Injuries Semi-automatic pistol

Slide 22: 

Myths and Mechanisms of Firearm Injuries Rifles

Slide 23: 

Myths and Mechanisms of Firearm Injuries Shotguns

Slide 24: 

Myths and Mechanisms of Firearm Injuries Anatomy of the Cartridge Shotgun Handgun Rifle Primer Flash Hole Powder bullet Powder Primer Wad Shot

Slide 25: 

Myths and Mechanisms of Firearm Injuries Small arms powder made of: 1. Nitrocellulose base, or 2. Nitrocellulose / nitroglycerine mix -Smokeless powder is NOT an explosive (black powder IS) -Grains come in different shapes and sizes -The smaller the grain the faster it burns Some Powder basics:

Slide 26: 

Myths and Mechanisms of Firearm Injuries

Slide 27: 

Myths and Mechanisms of Firearm Injuries 3. Ballistics of firearms. Science of travel of projectile in flight Divided into 3 parts: Internal (travel within the gun) External (gun to target) Terminal (wound ballistics)

Slide 28: 

Myths and Mechanisms of Firearm Injuries BANG! (what happens when the trigger is pulled?) Primer fires Intense flame created by primer fills chamber Powder burns, creates large gas expansion Huge pressure generated pushes bullet -The more complete and instant the burning, the more efficient the expansion of gas The tighter the hold of the bullet in the cartridge, The tighter the fit in the bore,  the more efficient use of the gas I. Internal Ballistics – what affects what?

Slide 29: 

Myths and Mechanisms of Firearm Injuries A little bit of physics… I. Internal Ballistics – what affects what?

Slide 30: 

Myths and Mechanisms of Firearm Injuries II. External Ballistics – gun to target

Slide 31: 

Myths and Mechanisms of Firearm Injuries II. External Ballistics – gun to target

Slide 32: 

Myths and Mechanisms of Firearm Injuries III. Terminal Ballistics – Wound Ballistics What happens when the bullet hits the target?

Slide 33: 

Myths and Mechanisms of Firearm Injuries Bullets produce damage in 3 ways: 1. Laceration and crushing 2. Cavitation: a) permanent cavity: b) temporary cavity. (tissue splash) 3. (Shock waves) (U.S. Dept of Defense) III. Terminal Ballistics – Wound Ballistics

Slide 34: 

Myths and Mechanisms of Firearm Injuries IV. Wounding mechanisms – Wound Profiles Many tissue simulants have been tried, few are accurate (eg: animals, clay, soap, water-soaked phone books...). Valid tissue simulant – 10% Ordnance Gelatin Calibrated against various living animal tissue Shots into this substance  wound profiles Accuracy verified by comparing with human autopsies. Now: Scientifically valid measurement tool Different projectile effects can be compared. Principles of wound ballistics can be studied. Can predict wounding potential of various projectiles. Fackler, et al. J Trauma. 1985 Fackler, et al. Wound Ballistics Review. 1994

Slide 35: 

Myths and Mechanisms of Firearm Injuries .32 Cal. Silvertip Winchester -soft lead -Non-fragmenting, expanding -Velocity: 940 fps (similar to present day .22 cal) Neck A. Handguns and Rifles IV. Wounding mechanisms – Wound Profiles Fackler, et al. Annals of Emergency Medicine. 1996

Slide 36: 

Myths and Mechanisms of Firearm Injuries M-80 7.62 mm NATO cartridge: -Full Metal Jacket -Non-fragmenting, Non-expanding -Velocity = 2800 fps IV. Wounding mechanisms – Wound Profiles

Slide 37: 

Myths and Mechanisms of Firearm Injuries Mannlicher Carcano 6.5 mm -Full metal Jacket -Non-deforming, Non-fragmenting -Velocity = 2085 fps IV. Wounding mechanisms – Wound Profiles

Slide 38: 

Myths and Mechanisms of Firearm Injuries .45 Cal Automatic pistol - full metal jacket - velocity = 870 fps IV. Wounding mechanisms – Wound Profiles

Slide 39: 

Myths and Mechanisms of Firearm Injuries M-16 .22 Cal Military Rifle -Full Metal Jacket -Fragmenting rifle bullet -Velocity = 3035 fps IV. Wounding mechanisms – Wound Profiles

Slide 40: 

Myths and Mechanisms of Firearm Injuries Winchester .308 Caliber Hunting Rifle (civilian) -civilian equivalent of military M-16 -Soft Point bullet -Fragmenting bullet -Velocity = 2,900 fps IV. Wounding mechanisms – Wound Profiles

Slide 41: 

Myths and Mechanisms of Firearm Injuries B. Shotguns 12 gauge shotgun - 1 oz slug - Velocity = 1510 fps IV. Wounding mechanisms – Wound Profiles

Slide 42: 

Myths and Mechanisms of Firearm Injuries 12 gauge shotgun - 27 pellet #4 buck shot - Velocity = 1350 fps IV. Wounding mechanisms – Wound Profiles

Slide 43: 

Myths and Mechanisms of Firearm Injuries 12 gauge Shotgun -169 pellets, #4 shot - Velocity = 1200 fps IV. Wounding mechanisms – Wound Profiles (Letterman Army Institute of Research)

Slide 44: 

Myths and Mechanisms of Firearm Injuries IV. Wounding mechanisms – Wound Profiles

Slide 45: 

Myths and Mechanisms of Firearm Injuries V. Myths of Firearm Injuries and Wound Ballistics: a) Myth of High Velocity: False dogma: 1. Tissue damage is directly related to bullet velocity. 2. High vel. missile injuries require aggressive resection. 3. Low vel. missile injuires require little or no treatment. 1960’s – Vietnam war, introduction of M-16 rifle (bullet speed = 3100 fps): - GSW severity increased significantly - The M-16: “massively destructive” “devastating wounding power” - High velocity became synonymous with “devastating killing power” Rich, et al. JAMA. 1967 Dimond, et al. J Trauma. 1967

Slide 46: 

Myths and Mechanisms of Firearm Injuries 1974 – Rybeck, et al. - High vel. Injuries cause temporary cavity 30x diameter of missile. - this tissue “would not survive” -  core of tissue would have to be excised!! -  equates to an amputation of almost any wound to arm/leg a) Myth of High Velocity…. V. Myths of Firearm Injuries and Wound Ballistics: 1975 -The Nato Handbook: Emergency War surgery (U.S. Govt. Printing Office) Rybeck, et al. Acta Chir Scand. 1974

Slide 47: 

Myths and Mechanisms of Firearm Injuries V. Myths of Firearm Injuries and Wound Ballistics: BUT: History of small arms development shows us differently: -Late 1880’s  largest increase in vel. of small arms projectiles. - From 1,100 to 2,400 fps - Invention of smokeless gun powder and jacketed bullets - striking decrease in wounds severity reported from all battlefields !!

Slide 48: 

Myths and Mechanisms of Firearm Injuries .38 Special Velocity = 880 fps Remington .357 Magnum Velocity = 1400 fps V. Myths of Firearm Injuries and Wound Ballistics:  Despite the 60% increase in velocity, the shape and size of both temporary and permanent cavities are very similar, Fackler, Emergency Medicine Clinics of North America. 1998

Slide 49: 

Myths and Mechanisms of Firearm Injuries M80 7.62 mm NATA cartridge Velocity = 2800 fps M-16 .22 Cal Military Rifle Velocity = 3035 fps V. Myths of Firearm Injuries and Wound Ballistics:  Despite similar velocities, M-16 produces significantly more injury. Bullet fragmentation is predominant reason for M-16’s increased tissue disruption Fackler, Emergency Medicine Clinics of North America. 1998

Slide 50: 

Myths and Mechanisms of Firearm Injuries b) Shock waves and Injury V. Myths of Firearm Injuries and Wound Ballistics: 1940’s: Harvey, et al. Surgery. 1947 1980’s: Suneson, et al. J Trauma. 1987, 1988, 1989 1990’s: Ordog, et al. J Trauma. 1994 Present day lithotriptor:

Slide 51: 

Myths and Mechanisms of Firearm Injuries V. Myths of Firearm Injuries and Wound Ballistics: c) “sterility” of bullets High temperatures inside gun barrel DO NOT sterilize bullets ALL gunshot wounds are contaminated. Use of antibiotics has virtually wiped out beta-hemolytic strep from battlefields (major cause of mortality prior to use of penicillin)

Slide 52: 

Myths and Mechanisms of Firearm Injuries V. Myths of Firearm Injuries and Wound Ballistics: d) Size of temporary cavity determines tissue disruption: .308 Winchester: 2800 fps 7.65 mm Browning: 900 fps -Most temporary cavities are relatively shallow compared to permanent cavity. -Temporary cavity is of very short duration. -Type of tissue significantly affects the wounding potential of temporary cavity: Lung Muscle Liver/Spleen/Brain Bone Fluid filled organs -In general, a faster bullet will produce a larger temporary cavity.

Slide 53: 

Myths and Mechanisms of Firearm Injuries e) Sensationalization by the Entertainment Industry: Bullets do not possess enough momentum to significantly move a human body. There is often no immediate reaction after being struck in the torso. V. Myths of Firearm Injuries and Wound Ballistics: MacPherson D. Wound Ballistics Review, 1994

Slide 54: 

Myths and Mechanisms of Firearm Injuries 4. Clinical Evaluation of G.S.W. – Role of E.P. The Emergency physician: - in ideal position to evaluate and document wounds before they are distorted by surgical intervention. - must resist temptation to make assumptions about findings  interpretations are correct in only 47% of cases 1. - do not describe wound as “entrance” or “exit” without indicating physical features of each. - must provide complete documentation of all wounds  in 59 patients, only 75% of all actual wounds was documented 2.  in 258 GSW’s, accurate anatomical locations were described in only 37% of wounds 1. Busuttil A, et al. Police Surgeon. 1990. 2. Marlowe AL, et al. Proc Am Acad For Sci 1996.

Slide 55: 

Myths and Mechanisms of Firearm Injuries Clinical Evaluation of G.S.W. – Role of E.P. Exit Entrance

Slide 56: 

Myths and Mechanisms of Firearm Injuries Clinical Evaluation of G.S.W. – Role of E.P. Entrance Wounds:  Divided into 4 general categories according to range of fire: I) Contact ii) Close Range iii) Medium Range iv) Indeterminate  When examining entrance wounds, remember: The size of entrance wounds bears no relationship to the caliber of bullet that inflicted it.

Slide 57: 

Myths and Mechanisms of Firearm Injuries 1. Entrance Wounds – Contact wounds Clinical Evaluation of G.S.W. – Role of E.P. All material (bullet, gases, soot, metal fragments) is driven into the wound Muzzle contusion

Slide 58: 

Myths and Mechanisms of Firearm Injuries 2. Entrance Wounds – Close Range Clinical Evaluation of G.S.W. – Role of E.P. Distance of less than 6 inches Dispersion of soot (which can be wiped away)

Slide 59: 

Myths and Mechanisms of Firearm Injuries 3. Entrance Wounds – Intermediate range Clinical Evaluation of G.S.W. – Role of E.P. -Tattooing is pathognomonic Tattooing cannot be wiped away. (soot can) Density of tattooing is dependent on the distance & caliber -Generally found at distances of 60 cm or less.

Slide 60: 

Myths and Mechanisms of Firearm Injuries 4. Entrance Wounds – distant range Clinical Evaluation of G.S.W. – Role of E.P. No tattooing or deposition of soot Indentation of skin creates Abrasion collar friction b/w bullet and skin (not caused by heat of bullet. palms and soles won’t have abrasion collars. Angle of impact depends on shape Cannot determine distance

Slide 61: 

Myths and Mechanisms of Firearm Injuries Clinical Evaluation of G.S.W. – Role of E.P. Exit Wounds Skin edges are generally everted Abrasion collars and soot are not usually associated with exit wounds Tattooing is never seen at an exit wound Are NOT always larger than its corresponding entrance wound May not appear directly opposite the entrance wound.

Slide 62: 

Myths and Mechanisms of Firearm Injuries C. Other Evidence: Clinical Evaluation of G.S.W. – Role of E.P. Opportunity to recognize, preserve, or collect short-lived evidence. Clothing can provide important information. Therefore, place each item in its own separate paper bag. -Every bullet and jacket has its own “fingerprint” Try not to obliterate these marking by removing a bullet with hemostats or pickups

Slide 63: 

Myths and Mechanisms of Firearm Injuries ”A meticulous evaluation and written description of gunshot wounds by the E.P. can save a very long and tiring process of legal testimony brought on by criminal events”

Slide 64: 

Myths and Mechanisms of Firearm Injuries The End.