I have nothing but good luck with the big 7mm wildcats from the Rem Mag up to the AM. All work very well. Most critical is bullet selection and matching the bullet to the game being hunted.
That said, if someone came to me telling me they wanted me to build them a rifle for elk hunting out to 1200 yards, I would look them right in the eye and tell them to go with a big 338 magnum. There are many to choose from but the fact is, for this specific big game animal, especially mature bull elk at ranges over 1000 yards, if your intentionally building a rifle for this purpose, you would be much better served with a heavier, larger frontal area bullet for these big tough animals.
Again, I am not saying the big 7mms will not work, hardly the case but again, personally, if I were setting a rifle up to take elk at ranges out to 1200 yards, I would choose 1 of 4 338 chamberings, 338 RUM, 338 Edge, 338 Lapua or 338 AX. The choice would come down to what receiver would be used.
Recoil would not be much of an option because of muzzle brakes but for shear game taking ability, I would have to recommend a 338 over the 7mm.
Had you said deer or similiar size game, I could recommend nothing better then the big 7mms but for elk at these ranges, Its wise to step up in caliber.
Again, not saying in any way that the big 7mms will not cleanly and efficently harvest elk at these ranges, that is not the case, I just personally feel there is a better caliber for this specific purpose.
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