Zimhunter; Congrats on your .458s. Equivalent ballistics from a 22" .458 WM is possible from my #1 Ruger in .45-70 with a long throat so bullets can be seated as long as possible/practical.
But, I'm wondering -- since you've never chronographed your loads -- why you seem to believe the book values that, without doubt, were from a 24 - 25" barrel? The Ruger 77, I once had, I should have kept as it was about ideal in overall length, weight and handiness given its purpose -- except for the too long throat which the action didn't allow adequate use of. The CZ did.
Anyway, not knowing your load, you probably are getting about what my Ruger #1 was making from the 500gr Hornady before I had the mod made on the throat. It was making 2000+ fps from the factory at safe, tested psi. The long throat allowed another 185 fps. That rifle, all up, with scope and 5 cartridges in a cartridge holder on the stock goes 8.6 lbs. I don't mind shooting it, but I wouldn't want it any lighter. And it's OAL is 38.5", almost as short as yours while still using a 22" tube. I think you're loosing about 200 fps from wherever your load might be from a 24".
So yes, a 500gr at +/- 2000 fps will kill anything on Earth assuming the right bullet and placement within range. But I WOULD NOT WANT THE MUZZLE BLAST, NOR WOULD THOSE NEXT TO ME!!!!!!!!
Bob
www.bigbores.ca 
