Grizzly, Corbon, Garrett, Buffalo Bore & HSM all make suitable "bear loads" in the 400-460gr range.
There are some good suggestions right there.
I handload and my choices are either the Beartooth bullets Piledriver Jr or CastPerformance 420 WFN at somewhere between 1650 and 1750 fps, let accuracy set the speed.
H322 has been the best powder in my rifle.
I came up with one load, AA2495 and the Piledriver Jr, that was fast and accurate, over 1800 fps, but it kicked so hard I hated shooting it.
