The 7mm Ultra mag is an impressive round.That being said,600 yards is a LONG way out there.I cannot imagine anyone wanting to take a shot at a large animal at that distance,there are just to many variables involved,ie wind,animal movement,etc. to ensure a humane kill shot.I am guessing that you do not have alot of experience with this round,and ALOT of experience is what it takes to make long range shots.I have been shooting the same rifle for six years now,am sighted in dead on at 200,but I am still cautious when the range goes much beyond that.Invest in high quality optics if you want to start taking long shots(everyone has their fav. brands so I won't start that argument!),but most important,study the ballistic charts for your round,figure its max. effective range,and then go out and burn box after box of ammo shooting at that range(not just assuming the charts are correct).This can be expensive, but is vital to ensure no animals are left crippled.Remember,the anti's get their ammo from the mistakes we make.....and this sounds like one waiting to happen.....