[Garvin]

I have fired at 500 Yards (457.2 meters), using 5.56mm (M16A2) slow fire on the range for 21 Years in the Marine Corps. Depending on the wind you can get a very close grouping with iron sights.

[Garvin]

https://www.quora.com/What-do-you-have-to-do-to-get-an-Expert-score-in-the-US-Marine-Corps-rifle-and-pistol-qualification-tests-For-rifles-what-are-Tables-1-and-2-How-many-points-are-you-given-for-hits-on-the-different-sections-of-the-targets