ok, I'll open this can of worms.
700's do not lock the action on safe anymore, haven't since 1980, if you want to have a rifle to take elk at 600 and beyond, you need a few things, first accuracy, you should have 1/2 moa accuracy, that will place the bullet within 3" or so of point of aim IF you have a good grasp on ballistics, and know where your bullet will be at that range.
You need a drop chart matched to your load that has been proven in the field, you need a caliber that retains 1000 ft/lbs of energy at the max range you want to shoot.
and you need practice. I've been in this game awhile and would not hesitate on a 600 yard shot.
caliber choices will start around the 270 Winchester on up.
RR