Trajectory was the term I was looking for - lots of studies have been conducted on the subject.
The experts are probably still working on this type of tests.
I've seen other posts on this subject and I read them. My brain only works at its own pace so I'm just catching up with this concept.
Considering the shooter didn't go far prior to getting the second shot off (but he may have stood up and/or changed position), there may be little difference in the results from the casings. But the results may be different enough to suggest Lt. G didn't fire the gun himself especially the second time it was fired.
The second shot may have been from a standing position, allowing an unobstructed casing to end up a greater distance away.
Because, if the second shot was fired by the Lt.'s own hand, he'd be low to the ground at that time thus his hands would be too.
Am I correct that one casing was found a (much) greater distance away than the other?