Thanx for the responses.
I can get (when available) loaded .455 Webley cartridges by Fiocchi thru a dealer here in Canada, but I wasn't sure if I was looking at the same dog!
I also wanted to be sure I could follow .455 Webley reloading specs as I have only seen for that cartridge, never .455 Colt. And although it is not a heavy (
) round, I didn't want to 'just give her a try' sort of thing!