In recent rears the four basic jobs done by dies has had an addition, that is, the factory crimp die should at least be considered in your sequence of dies/operations to perform especially for pistol cartridges.    The factory crimp die is the last step in the reloading process and resizes the case a final time then places a crimp on the case mouth to better hold the bullet.    This final resize compensates for some of the bulge that might have occurred when the bullet was seated.   

Unscrew the adjustment screw at the top of the die.    With no case in the shellholder and the ram at the top of it's stroke, screw the die in until it just touches the shellholder.    Back out the ram, place a resized (not flared) case in the shellholder and run the ram to the top of it's stroke.    Now screw in the adjuster screw at the top until you feel it just touch the case mouth.    Back the ram again and screw in the adjuster screw another half turn.    This should give you a moderate crimp.    After testing a few rounds you want more or less crimp, adjust the screw accordingly.      

When I use a factory crimp die I don't allow the seater to crimp the case.    In order to not crimp with the seater die, unscrew the die body about one turn from it's normal setting, then readjust the seater plug in to set the proper OAL.    If you have a round of the correct OAL, back off the seater plug, place the round in the shellholder, run the ram to the top, then adjust the seater plug in until it just touches the bullet.    This should put you close to the right OAL, but you may want to tweak it a little.