HI , I myself have a 550d and use dillon dies lee dies lyman, rcbs and redding the lee die seem to be ok, i need to screw them down a slight more but have replased all the lock nuts with rcbs's lock nuts only because i like the idea of using the set screw to really lock it down to the die.
Here's another tid bit that some my find interesting,in my search to help in saving money i found that some of dillons shell plates are interchange able the 7.62x39 works great for .38/ 357 mag, just a tad sloppy, and the .44 mag shell plate also works with .45 acp, but it also is a bit sloppy, jut watch and look at those brass pin what have nubers on them they do need to be replase with different shell plates in order to turn the shelll plate from station to station, it sure is fun experamenting .
The only real complaint I have with the machine is that little plastic deal that holds each primer ecery time you move the lever , if the primer thing moves up a .001" of an inch it will crush it at them you stuck by haveing to put a little preasure on the primer tube to put a new primer into the primer catch deal, buy all in all its a good machine, have fun and make good ammo.
kevin