[–] hobbidlybzi 0 points 1 point 1 point (+1|-0) ago
https://www.military.com/join-armed-forces/marine-corps-weapons-qualification-course.html The US trains marines for this. With iron sights. Check out: https://www.trngcmd.marines.mil/Portals/207/Docs/wtbn/MCRP%203-01A.pdf look for "Holds for Iron Sights at 300 to 500 Meters/Yards"
https://www.wheretoshoot.org/ Put your area in and filter for 500yds+
https://invidio.us/watch?v=jJ3XwizTqDw <- That is exceptional. Doing that prone with a rifle just takes practice.
[–] chuckletrousers 0 points 4 points 4 points (+4|-0) ago
Sounds like old school USMC range. My best score ever was 247 out of 250 points by hitting the 4 ring three times at 500 yards but the US flag was kicking out at 60 degrees from straight down due to the wind. Still far short of a mile.