Yes, you can, provided that you use moonclips. I've fired .45 GAP in a S&W 625 with no problems like that. However, without the moonclip, the shorter GAP rounds slip forward into the cylinder, making ignition "iffy", if not impossible.
I'd add that you should only do this in a gun that can withstand the higher pressures of the .45 GAP. Since the S&W 625 cylinder can be "bored out" to take .460 Rowland, there shouldn't be a problem with this model. Earlier S&W's, or Taurii, or other breeds without the law, might be different.
