bearfat'
the Lee FCD' does not crimp like so many other crimpers. it is not a roll crimp, nor a taper crimp. it appears to combine both procedures without loosening the caseneck hold on the bullet just behind the crimp, like so many crimping dies can do. those crimping procedures can actually impede accuracy!
i do NOT crimp any bottleneck cartridges for a single-shot firearm. that is needless, because there are no other rounds in a magazine, as Mac' pointed out, that could be battered and have their C.O.A.L. changed in the process.
FWIW: i crimp every straight-walled cartridge whether for a revolver or for my Marlini lever action. i would also crimp all such rounds loaded for a Handi'. i believe such cartridges, and those of a mild taper, require a firm crimp to achieve proper ignition. i do not use the Lee FCD' for those rounds i'm loading right now, however (.44 and .357 mag's and specials). they seem to be accurate enough!
Casull:
i do not consider the Lee Loaders to be a 'successful' application in my experience. i gave up on them after only one caliber because of the roughness of the die (the Sierras' tech's come back to my mind) and the poor service i received when it was replaced. i also quit using them because of their neck-sizing-only capability; and their very mild loads....when using the supplied measures.... are not sufficient for what i want out of my choice of cartridges. (Lee Loaders are a 'last-resort' to me) i have taken a cue from others with more extensive experience to stay away from Lee, as well. i admit you've achieved sufficient accuracy for your hunting needs. my statement, however, is true as it was submitted. that's why i said, " i have looked at....." i greatly prefer RCBS, Hornady, and Lyman.
good hunting and shooting to you,
ss'