I'd have to see the gun, but the cylinder doesn't "look" cut for moon clips, and all of the 625's I have owned will fire 45 ACP *without* moon clips; although extraction is a pain in the neck.
Unlike revolvers designed for rimmed cartridges, the proper spacing is built into the clearances at the back of the cylinder.
That doesn't preclude that somebody has altered the gun, but are you saying a moon clip of 45 ACP's won't fit in the gun?
Right Walter- you cant load moonclip onto the cylinder at all! There is NO CUT
for it- Is it possible that the cylinder has been replaced?