Supposedly the overall cartridge length is the same for the .45ACP and the .460 Rowland. However, I just looked at the Hodgdon reloading site and it shows the .460 Rowland being .070 overall longer than the .45ACP. So I don't know about interchangeability.
The 45 ACP, 45 Super and 460 have to be loaded to a cartridge over all length that will work through the magazine. From any practical stand point they are the same length and powder capacity.
