I have always believed that once the game stretches past about 600 yds,bigger is better and there is no replacement for displacment,both in motors and bullets.Big,heavy,high Bc bullets come into play.Anybody can get the right elavation hold, heck even a blind sow can find a acorn once in a while,but it takes experiance to judge the wind,thats were the big high Bc bullets come into play,the wind does not bother them nearly as much.Optics also play a huge factor when the targets get waaaaay out there,think about buying the the best scope you can afford and then spend a little more,a varible of about 5-22 is about right,depending on conditions,even a 22 power can have some terrible mirage issue's on certain days,terribly distorting your target.On other cooler clear days,a 12-42 power scope is not to much magnification.
And last but not least,practise ,practise practise,get good,really good, before you ever try making a shot on live game,as usual just my .02 worth
R