I generally roll crimp all revolver rounds, with 2 exceptions.

I started taper crimping my 45 Auto Rim target loads because it resulted in better accuracy. This was determined empirically after using a favorite 185gr LSWC load made up in both 45ACP and 45AR brass. For my 45AR heavy field load using a 250 or 282 gr LSWC Keith type bullet with a crimp groove, I always roll crimp -- it is a very heavy load exceeding 45 Colt factory load power levels.

The other exception is if I am using plated bullets. I don't usually load those too heavy anyway, sticking to lead bullet load levels, so bullet jump isn't an issue. However, it does seem to cut down on fouling significantly and result in better accuracy. I think a heavy roll crimp on plated bullets may scrape or tear a significant portion of the plating off on firing depending on the pressure curve/load levels.

Regarding the mentioned "plated bullets" that could well be true in bullets designed for a semi-auto such as the .45 ACP. However, most of the jacketed bullets for revolver cartridges such as the .38/.357, .41, .44Mag/Special, .45 Colt, ect have the cannelure for roll crimping into.

A major factor to consider in the roll crimp vs. taper crimp question is what specific powder is being used. Powders vary from slow rate of pressure development to very rapid pressure developement relatively speaking. Unique is on the slower end of the scale and therefore ultimate performance benefits considerably when the bullet is held in place for a short duration while the pressure within the combustion chamber develops to near full maximum. It has been amply illustrated in posts above that the roll crimp provides that needed time interval to allow maximum performance when using the slower burning rate powders. If you choose for other reasons to use a taper crimp the use of a faster buring rate powder is warranted. Big Cholla

With the FCD you can taper crimp firmly enough to create a homemade cannelure in a jacketed bullet. They tell me this isn't good form but in my experience it works fine, and gives much better performance with slow powders.

I use the Lee FCD for all my revolver loads. I seat and crimp in two separate steps and believe that that's the way it should be done. With the FCD you cannot load a cartridge that will not chamber because of buckling. To get in and out of the FCD a case cannot be greater than the O.D. (I'm guessing SAAMI specs) for that cartridge. I also heavy roll crimp all revolver cartridges (just short of one full turn) and case life doesn't seem to be an issue (I never flare the case mouth any more than absolutely necessary) from light target loads to compressed charge magnum loads. I've gotten much better ignition of different speed powders using a heavy roll crimp. I use jacketed and Rainier, or Berry, plated bullets. Cutting through the plating has never been an issue.