RE: Bullet weight in 7mm magnum for elk?
Any bullet weight from 150 gr and up in 7 M (.284 calliber) will have sufficient sectional density to give you the penetration that you'll want. Although corelokts work on elk, they are much more suited for deer-size game. On the chance of a lifetime, make sure your bullet is the best you can get. I'd look into the nosler partition from winchester.