Ok...made that other post from my phone...I hate posting with that thing, the spellchecker plays tricks on me.
A 180 grain Nosler Accubond (or Ballistic Tip) launched at about 2,800 fps will have a good bit of power at 600 yards, the BC is pretty good...at it will expand at 1,800 fps, which is about the 600 yard velocity.
I would say Berger 185, but I have yet to see what they do at 1,800 fps...they'll probably work fine, I just haven't seen it yet.
This is the route I have gone myself...I've never hunted elk but I plan to in the coming years, hopefully several times. I built a rifle just for this purpose, its a Win M70 with a McMillan stock and a Vortex Viper HS 4-16x44 scope....I'll admit that 600 yards is pushing it, but it is
well within the realm of possibility...its not a real long range rifle (by comparison to a 338 EDGE), I like to call it a "medium range hunter"...death to any deer at 600 yards, I may call it 500 yards for elk...but still...its far more practical for me than one of these big magnums, and I learned long ago that I'm a MUCH better shot with something that doesn't kick like a mule...I have a 300WM, shot it enough over the years to wear the barrel plumb out...and I'm still a better shot at 800 with a 308 Win....thats why I say "familiarity trumps all".
As I have said before...I have nothing against the big guns, I just know I don't shoot them as good as I do the little ones.
EDITED TO ADD: Now I wouldn't exactly say I'm a recoil wimp
... I shot pretty good with my 300WM, but I have always been better with a 308...so when I spec'd my new rifle...I chose accuracy over power and have really taken a liking to my new 30-06.