When I was working on the guided bullet, one of the most important questions was, "What could U.S. military snipers/marksmen do on the first shot with issue ammunition?". My information is old, but it might be of interest.
IIRC:
Stationary, torso-sized targets could be reliably hit from water for a distance of 50 yards, though some claimed 75 yards. Stationary, torso-sized targets 600 yards away could be hit essentially all of the time. Stationary, torso-sized targets 900 yards away could be hit about 2/3 of the time. The main reason for missing long range shots was supposed to be shooter error in range estimation.
IIRC:
Stationary, torso-sized targets could be reliably hit from water for a distance of 50 yards, though some claimed 75 yards. Stationary, torso-sized targets 600 yards away could be hit essentially all of the time. Stationary, torso-sized targets 900 yards away could be hit about 2/3 of the time. The main reason for missing long range shots was supposed to be shooter error in range estimation.