I’m looking for a long range mountain rifle for hunting mostly caribou, deer and sheep. The two most likely candidate are these too calibers. What would you choose for a long range rifle ? Or should I consider something else for this purposes ?

I would take the 7mm mag. But I guess that either 1 would do the job. What ranges are you looking at.

.30-06, 7mm Mag, 7mmSTW, .300 Mag

any of those calibers will do the trick, i like the 7mm rem mag personally, but i also own a .308 win.

270wsm

270 or 7Mag will both work om thse critters at about any reasonable range. I would go with the 270 for less recoil.

I was looking for same kind of rifle,then I bought a Remington 700xcr in 270wsm. I installed a Burris Euro-Diamond 2.5x10x44mm with the ballistic plex retical. I used Warn bases and rings. Rifle is light enough for me and has the Tri-Nite coating for harsh weateher resistance. I chronograped theWinchester 150gr. Power-Point ammo at 3200fps. Winchester claims 3150fps. with their ammo out of a 24" test barrel.Very accurate too.

Either will work just fine. I own both still but the7mm rem mag has beenmy choice for antelope to moose game interms of a Cf for a number of years now. Excellent choice in bullets and performance has been JFL.

I'd say 300wm but of the two probably 7mm.. good luck, let us know what you get..

Oh, and if your going to be walking enough mountains for some the game you mentioned I would give thought to a Kimber Montana rifle.. Just a thought though...

Both those calibers are excellent choices for what you have in mind. I have hunted with both, and killed deer with both. What I feel is most notewothy is the fact that the .270 is pretty much done with bullet choices at 150 gr., and you have more options with the 7 mag if you wish to pursue it. The .270 seems to do best with bullets in the 130 gr, range, depending on twist, and the 7mag seems to shine with 140 rangeand higher bullets. You need to decide on what you wish to shoot bullet-wise for the game you wish to hunt, and make your choice accordingly.
I know that the devotees of each will chime in, but for my money, with deer-sized game at reasonable ranges, the .270 is a tough act to follow, and only a slight whisper away from the 7 mag in factory ammo