Brown Bear? With a 7mag? Seriously? What does the guide/outfitter have say about that? I'd try to start somewhere around 32 or 33 caliber, preferably ending up in the 375/416 range. just sayin'
I would personally use something bigger than a 7mm Rem Mag but if Phil thinks that a .30-06 is adequate, the 7mm Rem Mag should be too.
