Just some food for thought.
820 grain @ 4500 psi - 747 fps = 1016 fpe Sectional Density .348
630 grain @ 4500 psi - 821 fps = 943 fpe Sectional Density .268 (Superior SD compared to a 300grain .44Mag bullet)
433 grain @ 4000 psi - 922 fps = 817 fpe Sectional Density .184
412 grain @ 4000 psi - 943 fps = 813 fpe Sectional Density .175 (same SD as a 250grain .45Colt)
The 412grainer would certainly be OK for any deer at 50 yards don't you think?
Much debate over "killing power" formulas for sure. Whatever anyone may think of them, they may believe one to be more
"in the ballpark" than the others, or maybe even fairly accurate. I know that I have yet to find a ballistic calculator that asks what
propellant is being used. So I'm putting these 300grain@1300fps .44Magnum up in the hopes it may add even a little perspective to what we're speaking of here. I'm just guessing with that .44Mag load but it sounds like a plenty hot load to me so I'll use it for the comparison.
Most should agree a .58 630grainer has good sectional density, momentum, and great penetration potential (superior SD compared to 300grain .44Mag).
So I am running the numbers for the 630grainer@821fps/941fpe.
Comparing the momentum of a 300grain 1300fps .44MAG to that of a 630grain .58@821fps, the .58 scores 73, the .44MAG 55.
DV Formula believes that the 630grain load is good for Black Bear 350-500lbs, and thinks the same of a 300grain.44MAG@1300fps
The Thornily Stopping Power Formula (scored 169) thinks the .58 is good for Lion, Leopard, Grizzly Bear, Brown Bear, and that the .44Mag is good for Black Bear 350-500lbs).
The .58 cores a Taylor KO Value of 43. A 300grain .44Mag@1400fps scores 24.
So in theoretical math land the .58 scores equal to the .44Mag in a few of the "theoretical" formulas, and far exceeds the .44Mag it in the rest.
The momentum calculation and sectional density calculations, however, are not so theoretical. Rough estimations, but good for comparison between two calibers. The .58 edged the .44Mag out in sectional density and stomped it when it came to momentum. Momentum and sectional density seem to me to be key factors in penetration, which is a huge part of what we are after when speaking of any hypothetical Elk load.
Any way you slice it, that rifle is capable of leaving a lethal boo-boo on most any game. The real question for me, is "Will it put lots of Elk blood on the ground?"