It depends on your weather for seeing .270 at 300. I have a vortex viper 15-45 and can see .270 holes at 300 if the mirage is minimal and I use bright orange targets. Use shoot and see targets for best results. But frankly don't count on seeing holes past 200.
Zero your rifle at 200. 9" of drop for the .30-06 is about right. If I recall correct a fast 130gr .270 is bout 6" low at 300 with 200 zero. I zero all my center fires at 200.
I don't have a .243 but heavier would deal with the wind better I would think. Either way enjoy. 300-500 is fun.
