The complaint has been re-assessed, and the punishment issued was indeed valid. The punishment will remain, and we will no longer consider overturning the punishment.
A staff member and myself did a bit of an experiment, using the same distances (as logged), -/+ 5m, the same weapon (M4), and came to the conclusion to get the damage dealt from the distances you were at, headshots were being made. Headshots are precise shots to be made, considering from the maximum distance you shot at (67m), his head would have been barely visible. So pretty decent shots, his armor was at 76hp prior to you shooting, so you took over 70hp from his armor. They don't seem like accidental shots to me.