.455 Colt from Dominion was, I'm pretty sure, loaded only with lead bullets. It was the longer .455 Mk I case loaded for Colt & S&W revolvers that were in service with Canadian government police and paramilitary organizations.
Many of these revolvers were, oddly enough, marked .455 Eley...
ETA: Nope, just found a picture of .455 Colt Dominion loaded with a jacketed bullet...