If you check the handloads in Hornady, Barnes, Hodgdon and Accurate, you'll get a better picture of what the .458 is capable of.

Personally, I seat bullets long, but even at SAAMI COL of 3.34" it's easy to get 2150 to 2200 fps from a 24" barrel using newer ball powders such as AA2230 and 2460, as well as H335. Also Australian stick powders promoted as Hodgdon's, they are temp resistant and work excellently, much better that the old IMR powders. H4895 is one for heavy bullets and H4198 works best for 300s and 350s. H322 and Varget do well for lighter and heavier bullets respectively.

My favorites for 450s and 500s are H335, H4895, AA2230 and AA2460.

With bullets seated long, as in the Barnes TSX's, they can be crimped into a groove or cannelure that equals or exceeds the Lott in COL giving identical to better performance with less pressure.

Bob
www.bigbores.ca