338 Lapua with 250 grain Scenars or the 250 grain lockpointe with a boattail. At longer ranges, the wind you see at 100 yards can be totally different in speed and direction out past 500 years. A heavier bullet with a high bc and good velocity is less affected by the wind than a lighter bullet.

For those long range shots, you need to be able to judge the wind out to your target.