This is a youtube video of a single shot made with a 50 cal at 1000 yards offhand. 2:30 long.
http://www.youtube.com/watch?v=u3BUnHiv6AA
http://www.youtube.com/watch?v=u3BUnHiv6AA
however, there's also a lot of luck in there too, since that's not exactly a sub-moa rifle