Re: 6.5x284 win
I don't disagree with the posts above, but, to me, the real reason to test at longer ranges is that once a rifle is accurate enough to go less than 3/8 to 1/4 MOA at 100 yards, you can't tell a lot shooting that close, and ammo becomes the limiting factor.
In my own 6.5-284, I had load with H4831SC and 142 SMKs that shot 1/4" to 3/8" groups at 100 yards with regularity, most closer to 1/4". When I got further out, it started shooting vertical groups as a result of ammo (primer) problems and high extreme spreads. At 200 yards or more, these problems become much more apparent. Changing primers gave me slightly larger groups at 100 yards (more often 3/8"), but *much* smaller groups at 800, 900 and 1,000, where the rifle gets the most use.
The beatings will continue until morale improves.