Looks like some one forgot that it was in between the turret and the hull of an M1.
"POWER!"
(grind sqeeech, crunch...)
"Hey Sergeant, i think my M4 wasn't secured...."[/
I have heard the snapping sound of a lower receiver when I slewed the turret on a Bradley.....stupid driver left it leaning against the smoke grenade launchers.......I mean I had a friend who heard it.....