remington 225 grain swift a frames....
i have not used on br bear, but on an eland, one shot at about 225yds, entered on a broadside shot, found perfectly mushroomed just under hide on other side, PH guestimated weight, 2,000lbs, a fairly large bull.
i love the 338wm, and loaded with the rem 225 a frames,a killer combo...but as you suggested, a 250 grain nosler partition is excellent as well...
fwiw, the 250 partitions and the 225 a frames print almost identical from my rifle, i use the 225 for fairly open areas, and if it's thick, the 250 get the nod.
just my $.02