I agree with Smith Crazy. In a S&W revolver, 45acp is as good, if not better than 45colt. It pains me to say that because I really love 45colt, but within the pressure ranges that S&W revolvers are suitable for, the 45acp or 45ar cartridge holds it's own against the larger powder capacity 45colt. This afternoon I reloaded some 45colt and 45acp rounds using the same 255gr lswc bullet. With 8.8 grains of Unique I was getting around 908 fps out of the 45colt. With 6.8 grains of Unique I was getting 956 fps out of the 45acp. I chrono'ed the loads at 15 ft from the muzzle. Both revolvers have 4" barrels. Both loads were equally accurate at 25 yards, and recoil was very similar, with the 45acp being slightly snappier but both pushing about the same.
Obviously the 45colt has a lot more case capacity, so in a Ruger, BFR, or Contender, the potential of the 45colt is greater than the smaller 45acp. That being said, I don't think you need to push a 250 or 270 grain 45 caliber bullet beyond 900 or 1000 fps in order to put down most game, or threats in the lower 48. Granted, your range may be limited to under 100 yards, but recoil is tame and follow-up shots are faster.
I loaded up some heavier 45colt stuff for the Ruger, today, as well. 200gr lswc's at 1175fps, and 250gr jhp's at 1150fps. Not max loads by any means, but heavier than I would ever try in my S&W's. I'll take the 45acp 255grainer's at 950 over any of the loads. These were shot out of a 22-4 with the 4" tapered barrel. I would think that in a 625 with a full-underlug 5" barrel they would be even more tame.
By the way, out of all the loads mentioned, the 200 grainers at 1175fps had the lightest recoil and grouped the tightest. Seems odd since they were shot out of the Ruger Vaquero with pretty crude fixed sights.