Rochelle,
There seems to be a never ending quest for an "all around rifle" and an "all round bullet" for "all around hunting." If only we had "all around big game" that were all the same size, structure, and toughness, then it would be a worth pursuit. You may notice that even this web site doesn't put deer under the "big game" category so I'm afraid if you are looking for optimum combinations for your quarry, then you'll need to vary your bullets a bit.

Elk, go with the 180gr partitions at a minimum - you'll need it for penetration.

Deer, drop back on weight to 150gr or so it doesn't just shoot right thru.

Regarding repeated sight-ins for different bullet weights I would recommend against it unless your rifle performs substantially different with the different weights. Without checking the tables, I'm betting that out to 300 yards there is not a substantial difference between 150's and 180's and what little there is could be accounted for mentally.**

**Probably a "huge" difference for "on the bench" target shooters; probably no material difference at all for "in the field" hunters.

EKM

Good judgment comes from bad experience! Half of elk hunting is knowing what NOT to do!