Will,

Interesting point you've made. You aren't the only one to shoot the Kreighoff 470 at 2250fps and report good "regulation" and accuracy. PH Rich Tabor, who I've hunted with quite a bit, loads his 470 Kreighoff to 2250fps with Woodleigh solids and reports that it is holding up fine and shoots well too.

One thing about 458wm doubles is that, at least in my experience, powder choice lets you have several full bullet weight loads at varrying velocities which will all shoot to regulation. But given that you've got to get the rifle to shoot to the original regulation there is, again - at least in my rifle's case, a velocity peak well below what you could push a bolt rifle with the same barrel length (given, of course the same chamber dimensions, etc...), or you could reregulate I suppose. My rifle is maxed out on velocity which will shoot to regulation, so far as I've found, with a mild to midlin' load of AA 2230 at 2145fps at the muzzles. 26" barrels really help I think.

JPK