I have just started reloading for this behemoth. I currently have 300 grain Hornady FTX Bullets and 500 Grain XTP , I have AA #(ullets. I loaded some of the 300 grainers with 36 grains of AA#9 and it seemed pretty stout but not excessively so.. I have been able to find very little load data for this bullet. As for powders I have on hand I have AA #9, 4227, 2400, unique and probably a few others that would work in this cartridge. If you have any accurate loads to recommend using what I have on hand I would appreciate it greatly.