Match your crimp to the bullet. If it has a cannelure, then roll crimp it, otherwise taper will do just fine.
I have a Taurus 455 (5 shot 45ACP Tracker) that I load 250gr 45 Colt lead flat nose bullets (from a Lee mould) into 45 ACP cases for. They have a cannelure, so I roll crimp.
I also shoot Berrys 230gr plated round nose from it and I taper crimp those.
Over the last 6 months Brian Peirce (sp ?) wrote a very good article in Handloader magazine about 45 ACP & 45AR in S&W 625s with load data. It stirred up a fair bit of discussion about headspacing in such revolvers as they no longer headspace on the case, but use the moon clip instead. Clearly, not an issue for 45AR. Sorry, but I can't remember which month it was in.