score:4
I'm not sure, but here is a good candidate:
Experts suspect White was killed while trying to disarm a 9-inch, 75-pound naval cannonball, a particularly potent explosive with a more complex fuse and many times the destructive power of those used by infantry artillery.
Biemeck and Peter George, co-author of a book on Civil War ordnance, believe White was using either a drill or a grinder attached to a drill to remove grit from the cannonball, causing a shower of sparks.
Because of the fuse design, it may have appeared as though the weapon's powder had already been removed, leading even a veteran like White to conclude mistakenly that the ball was inert.