If you are not going to be loading any lead bullets in the cartridges, only jacketed, then a (3) die set should be fine.
However, having a (4) die set, with separate seating & crimping dies, is best for lead bullets because the seating/crimp die, in a (3) die set, is trying to do both things at the same time & can give bad results sometimes.
Additionally, if your brass are not all the exact same length (not mine
) constantly having to readjusting the combo seating/crimping die is a royal pain. Having separate dies means you can tweek the crimp die, as needed, without affecting anything else. Lee's crimp die (FCD) crimp adjustment is one of the best & easily a reason in it self to buy their (4) die set, IMO.
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