During a field exercise at Ft. A.P. Hill in 78 or 79 a big dummy from PA loaded a belt of live ammo into an M60 - with the blank adaptor clamped to the front sight - and test fired it right above our heads from the top of the APC.
I happened to be looking towards the tree, with 4 or 5 guys sitting under it, at the edge of the woods when the bark started falling all over them. My mind went into the, "Wow, look at all that bark falling on those guys and how they're twisting, rolling around on the ground," mode.
My buddy cussed, pushed me out of the way (to get around the back of the APC), got up there and grabbed the M60 from the big dummy and smacked the stuff out of him.
The flash suppressor was twisted sideways and hanging off the barrel and the threaded portion of the blank adaptor that fits into the flash suppressor was missing. The clamp part was still on the front sight.
It happens. Whose fault was it? Armorer and gunner both at fault. Gunner was a big dummy and should have known the difference between blanks and live ammo. The armorer knew we were doing aggressor detail that day and should never have given the big dummy live ammo when he issued him the M60 with the blank adaptor on it.
Big dummy? Yeah, 6'6" tall and 255 lbs. Looked like a refrigerator in fatigues.