mauser06,
The bullet you are describing is the Nosler Partition. You should probably go with the 180gr.
Front section expands violently for maximum expansion and the rear section holds together and continues to penetrate.
Good for a light bear and also good for a heavier bear if you get lucky.
If you do run into one of the bigger ones you may not get the penetration you need with a lesser constructed bullet (which are great if you get a nice broadside presentation).