The "normal" standard for rifle accuracy is 1 MOA (minute-of-angle), which translates to center to center spread of 1 inch per 100 yards of flight (1-inch groups at 100 yards, 2-inch groups at 200 yards, 3-inch groups at 300 yards, etc).
As the range gets longer, variable factors like wind become more important, therefore if you have a nice 1 MOA gun, it's a lot easier to get 1-inch groups at 100 yards, than 3-inch groups at 300 yards, because the wind's influence on trajectory varies from shot to shot, and the longer the flight path, the more the wind will affect it.
If I understand, you're looking for 1-inch groups at 200 yards (0.5 MOA at 200 yards) or 1-inch groups at 300 yards (0.33 MOA at 300 yards). That's going to be a tall order, even if you're really spending the $$$.
I think you should seek 1 MOA at 100 yards, and if you can do better, be real happy
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