Results
The results of this study demonstrated how unpredictable spent cartridge casing ejection
patterns are even when many variables are controlled. A total number of 7,670 bullets were fired
from eight different firearms in the course ofthis study. Spent cartridge casing locations are
illustrated through the use of scatter diagrams and pie charts. During the presentation of this
information reference is made to quadrants one, two, three, and four. The quadrants are
orientated such that quadrant one and two are in front of the zero point and would indicate spent
cartridge casings being ejected infront of the study participant, while quadrants three and four
would represent the spent cartridgecasings being ejected behind the zero point and to the rear of
the study participant. A spent cartridge casing found inquadrant one or four would indicate
ejection to the right of the zero point, while spent cartridge casings found in quadrant two or
three would indicate ejection to the left of the zero point. When a spent cartridge casing position
is specified through angular reference a negative degree value indicates a cartridge casing behind
the zero point, while a positive degree value indicates a cartridge casing in front of the zero
point. Zero to 180 degrees begins tothe right of the participant and follows an arch to the left. In
both cases the zero reference is located at the zero stake in the center of the grid. See Figure 1
below for example.