Even assuming .5 MOA accuracy over that distance,a head shot would be a matter of luck.
I’ve seen Marine snipers shooting the 7.62 make repeated head shots at the range. It takes a very still day and a very good shot but the equipment is up to the task.
Think the rifle he is working with is probably better than .5 MOA. Probably more like .3 with a professional trigger man at the back end.
3 inches at 1,000 yards, it ain’t luck my friend.
Here’s a civilian getting .4 at 1000 yards.
http://www.thefirearmsforum.com/threads/338-lapua-1000-yard-accuracy-test.136428/