I'd agree with mysticplayer and go with a .300 RUM. I currently own a .30-.378 sako trg-s. As far as ballistics go the RUM is nearly the same, I haven't got a table in front of me but if I remember correctly it is within 100-150 fps. The big bonus's are the brass is alot cheaper, there is no belt and factory ammo is wayyyyyy cheaper.
Mine rifle has sat in the closet for almost 2 years now so I haven't done a run of reloads in a while. but the last time I did the I had "belt bulge" where the working of the brass in full length sizing (they were hunting rounds) creates an buldge just above the belt. This makes the round very hard to chamber if it is even possible. I had to take the whole lot of 40 to the range and chamber each round of the lot to see which had this problem. The RUM does not have this problem as it does not have a belt so brass life is much longer when full length sizing.
Barrel life, lots of burned powder and expensive hard to find actions are common problems with all the super mags so if you're set on one I wouldn't worry about it, as long as you know they are there.
If I had my time back I would have went with the .300 RUM, an almost identical cartridge with less drawbacks.
osborne