If you go by the record, this is it:
http://bulletin.accurateshooter.com/...at-1000-yards/
That is a 30 Cal into a 1.403 inch group of five rounds at 1,000 yards. That is smoking.
The record for 10 shots I believe is 4.2 inches, you can Google that.
I own a 6mm long range gun that has shot a 5 shot group of 4 inches at 1,000 in front of a half dozen witnesses.
Ed