An expanded study of shell casing ejection patterns, with important legal implications for law enforcement, has just been completed by the Force Science Research Center, with cooperation of the Los Angeles County (CA) Sheriff’s Dept.
Details and an analysis will be reported in the next issue of Force Science News, but FSRC Executive Director Bill Lewinski says that the new research tentatively confirms that “how a handgun is held has a more profound impact on the ejection pattern than caliber, ammunition, design or make of handgun.”
FSRC became interested in this subject 2 years after Lewinski was recruited as an expert witness for an Arizona officer who was charged with murder in the shooting of a female driver whom he alleged threatened him with her vehicle. An issue of credibility arose when a firearms examiner adamantly claimed the officer was lying about his position during the incident, based on where a spent shell casing from his semiautomatic was found.
Two preliminary FSRC studies conducted with single shooters firing a total of 150 rounds concluded that ejected-shell placement can vary radically depending on how a weapon is held. After Lewinski’s testimony to this fact at trial, the officer was acquitted.
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The new study involved about 60 officers from LASD, each firing at least 110 rounds with a variety of handgun models held in 11 different positions. “Without a doubt, how a gun is manipulated when shooting has a greater impact on ejection pattern than any mechanical influence,” Lewinski says. “With a study of this extent, the empirical reliability is very high.”
This automatically becomes the largest study of its kind–because it is the only study that has focused on physical manipulation as a factor in ejection patterning. “Everyone else has come at it from the mechanics of the gun, the quality of ammunition, even the spring tension of the magazine on the slide,” Lewinski explains.
“This is a tragedy. Because of inadequate and incomplete ‘evidence,’ officers have been erroneously charged with capital crimes. Ignorance has been used to accuse these officers. A study of this nature should have been done long ago, and with all the firearms experts around who claim to speak with authority on this subject, it’s absurd that it wasn’t.”
Under the coordination of Lewinski and Lt. Joe Hartshorne of the LASD Homicide Investigation Division, the latest research was led by Dave Karwoski, an FSRC Technical Advisory Board member with 30 years’ experience as a sheriff’s deputy and firearms instructor. He was assisted by Mark Peterson, a law enforcement student at Minnesota State University-Mankato, home of the FSRC.