Well, I never owned nor shot a .458 Win. Mag. but I used Barnes .458 Win. Mag. loading data for my .458 Alaskan (similar case capacity)& had no trouble breaking 2,200fps with 500gr. Hornady bullets, just as they showed & with several powders. My vel. was about 40fps higher than theirs was, which might have been due to my not using their bullets.