I have taken Elk and deer out to 400 yards with the 180gr X in a 300 win mag. I also took one moose at 400 yards with the same load.
I only have one deer out to 300 yards on the 300 Weatherby mag so far. Two other deer were under 250 yards (all of them one shot kills). My brother has used the 180 nosler partitions for over 8 years now in his 300 Weatherby mag and has shoot deer, elk and a black bear all with excellent results. The 180 grain triple shock will be fine. If you want to go after the big brown bears them maybe you might want a bigger caliber or heavier bullets. I haven't hunted them but most of the guides I talked to in Alaska want the 338 mag or larger for them. Need the knock down power, that is a lot of bear to stop.