Re: 300 RUM enough gun for elk @ 600 yards?
Obviously, you've got your answer, yes, the 300 RUM is definitely enough for elk at 600. Even past 1,000. You're wise for considering lower powered options, ie the 300WM.
What hasn't been mentioned yet, is ammo for the 300 WinMag is far more available than that of it's Ultra Mag counterpart. In addition, the 300 RUM is a barrel burner. The 300 WinMag is also considered a barrel burner, but nowhere near as much as the Ultra and with proper reloads (if that is something you may wish to consider) loads can be rolled so as to ease the corrosion on your throat, thereby extending the life of your accuracy.
Run as fast and as long as you can... my little friend
will catch up and set you free.