So.... you dont know enough about cartridges to be able to chose one, but you shoot at game at 600 yds?
What I "know from what I have been taught" may not be correct for an elk.
Here is what I know from actual experience..., I can reach out and place a shot at 1000 yards with a .308. I know that the same is true for me with the .300 Winchester Magnum, and with a 6.5 x 55 Swede, all with factory ammunition. I know I can reach out and place a shot with a .223 in factory ammunition at 600 yards. So in answer to comments about the opening of this thread, yes I can place a shot to harvest game at 600 yards, placing is one thing, what the bullet does when placed is another.
I have never done so at 600 yards, otherwise I would not need recommendations. I would simply go with what personal experience and observation had demonstrated. I never stipulated that I "shoot" game out to 600 yards, nor that I plan to do so.
I prefer when harvesting deer to get within 300 yards with a .308, and would perfer the same if I was using a .300 Win Mag or a 6.5 x 55. I would not, myself, use a .223 for deer, as a personal preference. With my muzzleloader, I prefer 100 yards or less. I have never hunted Elk. Hence the need for adivice from those who have.
I have been shown on paper that the 7mm Remington Magnum has a rather flat trajectory out to 500 yards, I know the .300 Win Mag has a good trajectory, as well as the .338 Winchester Magnum, and the .30-06 and .270, as well as the .300 WSM, the 8mm-06, the 7.62 x 54R, and several others ..., that will reach that range with little trouble.
(I read a bunch of the previous threads on the THR concerning elk and caliber choices, and some limited the discussion to a few cartriges, and others discussed ranges well below 600 yards. So then I posted this thread.)
I have been asked to teach a fellow how to successfully place a shot at 600 yards, and he plans to hunt for elk. The max range was his choice. I was looking for information from experienced folks as to a specific factory load or several. I could then look into those loadings, and then be able to inform the student (hopefully) that he needs to learn how to accurately shoot at a much closer range, and then teach him how to get the animal within that range.
When first asked by him, I immediately thought Remington 700 with a Leopold 3x9, in .30-06. There are lots of different factory loads for that cartridge, and I would recommend something heavier than a 165 grain spitzer boattail bullet. That round in my experience tends to be comfortable to shoot. IF he absolutely thought he needed something with the word "magnum" in its name I'd say the same rifle but in .300 Win Mag. (And with either, get him to get within 300 yards)
I did not mention more details as I wanted to limit skewing the responses too much.
It appears that my "book experience" was correct, based on the responses on actual experience with cartridge choices and ranges to use those cartridges. Thank you.
LD