Yeah, that is the question. The old heavily packed .458 loads worked fine until they got some age on them and were subjected to the high heat of the tropics. I have a friend who is the PR for Hodgdon and he didn't have good stats on the Hornady Win Mag loads. He recommended Lott loads of IMR 4320 at 76.5 grams and MAX at 85 grains for 2,330 fps using the 500 grain Spire Point bullet. With IMR 4064, the starting load is 71.1 and MAX is 79 grains for 2,230 fps. These are older powders in a much larger case than the Win Mag. He felt that they would be less likely to fail in a tropical situation. Hence, the reason for the Lott in the first place. I figured I'd wait until more hunting reports came in on the Hornady Win Mag load. Until then the Win Mag is ALL I'd ever conceive of needing in North America.