Originally Posted by Riflecrank
BENCHMARK might be a good one for 400 to 500-grainers.
It has about best ThermoBallisticIndependence from overall take on published trials.
It would be good to make up a load that gave about
2150 fps with 500-grainer
2250 fps with 450-grainer
2400 fps with 400-grainer
from a "standard .458 WinMag rifle."
Benchmark Loads, pun intended.
Used as standard measuring sticks for comparing MV of different rifles of whatever barrel length/twist/groove/etc. at whatever temperature.

Sir Ron,

BENCHMARK is also great for the 550's too!
Using 73gn behind the 550gn Woodleigh l'm getting just under 2100fps (2080fps to be exact)
This is from a 24" barrel out of my 'standard' Zastava and loaded to an OAL of 3.340"

Russ

You'll probably never NEED a gun. In fact I hope you never do. BUT IF you do, you will probably need it worse than anything you've ever needed before in your life...