Why in God's name would you want to?
There's no way in hell I'd chamber my gun that way. I love my hands and my eyes too much to risk loading the wrong caliber.
Even though the .480 does not have the energy of the .454, I'm sure there is something different enough about the cartridge to make this risky at the very least.
Why wouldn't you just buy the .454 loads? Or load them yourself, down a bit? The .454 kicks hard, sure, but it's livable.
~Robert (Denver, CO)