Gun Shot Residues

GSR Deposit Dynamics

Forensic Scientist Wayne N. Hill Sr., who specializes in Homicide Events Reconstruction video taped this image of an FSDC brand 1911A1 .45 ACP semi-automatic pistol firing. The video camera's shutter speed was set at 1/10,000th second and it caught the pistol as it's slide was just starting it's rearward cycling under recoil.

The bullet is blurred, but visible at the edge of the image. The muzzle flame is visible, along with the primary waves of graphite dust, soot, Barium, Lead and Antimony that are being propelled forward from the muzzle.

Gunshot residues are composed of soot, Lead, Barium and Antimony from the discharging cartridge primer compound. The soot portion of these GSR's (Gun Shot Residues) is comprised primarily of graphite dust. Graphite which is literally the "lead" used in a pencil, is a form of carbon which doesn't burn at 2000 degrees Fehrenheit. So since raw smokeless propellants burn too quickly and thereby would over pressurize the firearm they were used in and blow it up, the burn rate of the propellant powders must be regulated. This regulation of how fast the powder grain burns is done by coating the grains with varying amounts of Graphite powder. Since the Graphite powder doesn't burn the unburnt Graphite powder is expelled from the muzzle as soot. The traces of the elements Lead, Barium and Antimony come primarily from the discharging primer's explosive compound, which contains Lead Styphnate.

There is a small puff of soot and smoke visible over the pistol's chamber area. This puff of GSR is vented when the slide first begins to retract, opening the breech/chamber area. This contains the microscopic GSR particles that are frequently deposited on the shooter's weapon hand, as this GSR particles drifts down toward the ground.

Since the shooter's hand is gripping the firearm, the palm is covered and protected from these settling GSR materials. This is why GSR found primarily on the palms indicates someone has HANDLED a previously fired weapon. Whereas GSR found on the web and back of the hand instead indicates the shooter of a weapon. The photo below shows a firing .357 Magnum Revolver and shows the Propellant Flame escaping from the Muzzle, Barrel Ports and Cylinder Gap. All these areas where the Propellant flames are escaping from will also be expelling Soot and GSR Particles as well.
Revolver firing a gunshot.

However, if there is a cross draft or strong breeze/wind, particularly during outdoor shootings, this small puff of micro fine dust can obviously be blown away from the hand. This is one of the reasons why a positive test for GSR indicates the subject has handled or discharged a firearm, while a negative test indicates nothing of certainty.

Examiner Hill has been found qualified by and given expert testimony in the Courts of: AK, AZ, FL, GA, Hawaii, ID, IL, KY, MI, MA,MN, NC, OH, OK, PA, SC, TX, W. VA and WI.

In September of 1997 Examiner Hill became the first American, since President Ferdinand Marcos was deposed, who was allowed to give Expert Testimony before two Philippine Senate committees. Examiner Hill testified relating his findings regarding the Murder with Staged Suicide (murder/attempted coverup) of Philippine Navy Ensign Phillipe A. Pestano, whose body was posed in his ship board cabin, while at sea.

E-Mail: whill@qconline.com     
P.O. Box 873, East Moline, IL 61244-0873

Examiner Hill's Professional and Resume pages

Photographs of muzzle/Cylinder Gap/Barrel Ports flames from .22-.44 Magnum

Firearm Discharge photo prints and training materials available to order.

Updated list of every school that offers a forensic science technician program in the US.

International Academy of Forensic Examiners and Investigators. (Forensic Science Training Available)

Vidocq Society, an elite association of forensic experts who lend their expertise in solving difficult and unsolved homicides.

American College of Forensic Examiners

Zeno Geradt's Forensic Resources Page (Vast resource of Forensic Info-Recommended)

American Police Beat newspaper

Mining Co Crime Site-Fascinating site for Crime & Detective enthusiasts.

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Copyright © 1996 Wayne N. Hill Sr.
This Home Page was created by WebEdit,Tuesday, November 26, 1996
Most recent revision Wednesday, July 01, 2009