When I served, we still hit the range with iron sights, but I am not sure if they do that anymore. Anyway, our range capped at 550 meters, and I managed to fire expert with the M14.
The M14, like the M1 before it, was substantial enough to settle in very well for the longer
ranges. A I recall, the regimen was something like, 50 meters-off hand, 100 meters-with sling, 200 meters-kneeling, 300/400 meters-sitting, 550 meters, prone or foxhole..
The M1 range was similar, except measured in yards, last being 500 yards.