wildcatter, In my rifle .454 cast boolits will chamber, but they're stuck and won't extract. .453 seems ideal, and fills the throat. I have found that using the Lee push through .454 die, followed by their .452 die, in my Rock chucker with a little imperial sizing wax is the way to go when sizing down the jacket bullets. I was bending the handle on my star sizer lubesizing the cast boolits from .458 to .453 in one go.
BD