Best caliber for big game at 400 plus yards

I've hammered an elk at 700yds and a kudu at 415yds with 200gr projectiles out of a 300Win Mag. Accuracy and shot placement are the keys along with a good bullet.

I watched a guy try his luck with a 30-378 Weatherby. Recoil was brutal, the brake was ear shattering and the ammo around 150 a box. He missed often.

Find a gun you can shoot.