I have the 300 rum and it is a very accurate round. The 7mm should be just as good. It would be best suited for heavy bullets of great construction because of high velocity. It will kill anything you need to kill... period! The recoil is strong but with practice you will find it manageable. Ammo is expensive but if you reload it is not such an issue.
As good as the core locks are, in the magnums I would go at least a 150gr bonded bullet. Your asking a lot for a 140gr bullet to stand up to that velocity at the closer ranges. Matter of fact, I'd look for a 160gr load if it were me.
The corelokt ultra should be fine as it's a premium bullet but i to would suggest the Nosler Partition. I use 160gr Noslers inmy 7 Mag for just about everything. The 150gr Scriocco is also a good bullet for long range shooting. I would try a couple of different loads & see which one shoots the best in your rifle.
First of all, if you haven't gone winter backpacking, it needs to happen in the near future. It puts a very unique twist on the summer version of the activity. Yes, it's cold but it's nothing that being prepared can't remedy. Beyond it's therapeutic and recreational value, I think it is a very good tool for the big game hunter as well. I don't think that you can spend too much time getting to know the ins and outs of the area that you hunt. And there is no better way to gain experience in...