Muley
I recently took a Buck Muley at 450+. the only way that can happen is by setting your equipement up for long range.I am a retired marine and shot not only competition but sniper.
1. find a bullet or handload a bullet your gun likes and shoots groups less thana inch at a 100 yard
2. find a scope with the magnification you are comfortable with. a 36x scope picks up every move , concider no more than 12 or 16x---use target turrets
3.shoot at each range from 100,200,300,400,500 and know were the bullet strikes at that range and set dials to that range or draw up a range card
4. realize you limits , not everyone can shoot at ranges exceeding 400+ yards . if you accuracy limit is 350 or 400 dont push it and wound a animal.
5.make sure your caliber can do what it needs at that range you want to hit. a 270 wont have the energy to put a elk down at 500 yards that a 7 mag will etc
if i can be of any help let me know