Since I reload all my ammo, I don't really know what sort of factory ammo is out there now for the .300 Wby.I'd say if you can find something with any of the following bullets loaded in it you'll be okay for just about anything:

Barnes Triple Shock
Nosler Partition
Nosler Accubond
Hornady Interbond
Speer Grand Slam
Trophy Bonded Bear Claw

Try some of each to see what shoots best in your rifle. I like a very stout bullet in my .300 Wby (like the ones listed above) because I often have shot opportunities of very short range. Lately my bullet of choice has been the 168gr. Barnes Triple Shock.