imho, lot of suspect advice in this thread...
if you've gotten yourself into a friendly competition out to 600 yards, you will definitely need some mechanism for determining the distance to the target, be it range finder, or pacing it off or whatever. it's just math, but it's important. WAY too many "long range hunters" can't tell the difference between 200 and 600 yards.
You will also want to get the dope for your rifle/ammo. There is a difference between "data" and "dope".
If you want to make hits, you will need to learn to spot your own hits or bring friends who can do it for you.
If you want to make first round hits, you will need to learn to make effective wind calls.
With properly set up and sorted out equipment, anybody can make hits from prone with a bipod/bag. If your competition involves shooting from positions other than prone, like sitting, kneeling, standing, leaning up against a tree, using shooting sticks, etc you will need practice (and ideally, some quality instruction)
if the ADL stock doesn't put your cheek in the right spot, or you've placed the scope where the eye relief isn't in the right spot, or the scope is canted, or the stock isn't bedded properly, or the length of pull doesn't fit you, or it's not focused properly, etc you will likely find shooting 600 yrds a little frustrating, as you won't be able to tell if the reason you hit sometimes and miss sometimes is the way you're pulling the trigger, or the gun, the ammo, the wind, etc.
good luck