Walkalong said:
The FCD for pistols crimps like any other, and can be adjusted wrong just like any other. it is the carbide ring that post sizes where to debate comes in.
= This comment is only for semi-auto pistol FCD =
I believe the FCD's carbide sizer ring's diameter was meant for typical jacketed diameter bullets (.355" for 9mm, .400" for 40S&W, .451" for 45ACP etc.) to smooth out any bulging of case neck from bullet seating for more "factory-like" finished reloads. Also, if the base of your case somehow did not get full-length sized completely (perhaps hot loads shot in looser factory barrel chambers that overly bulged the case base), FCD's carbide sizer ring will help further resize the overly bulged case bases to reliably feed/chamber (especially in tighter match barrels).
For me, the use of FCD for these purposes is fine but not for use with larger diameter lead bullets as the carbide sizer ring may post-size the finished case which results in reduced bullet diameter that decreases bullet-to-barrel fit. If you want to use the FCD with larger diameter lead bullets, you can either knock out the carbide sizer ring to use as a taper crimp die (to seat and taper crimp in separate steps to not shave the bullet when using heavy/negative taper crimp) or have Lee Precision replace the carbide sizer ring with a larger one (I think someone posted Lee charged $15 for this service but I would check with Lee customer service for current pricing).
Instead of using FCD "after" my rounds are reloaded (they stay in the die boxes), I do Quality Control check "before" my rounds are reloaded. During resizing, if I have a case that requires significantly more effort, I will do a barrel drop test with the tightest chamber I have (which are Lone Wolf barrels for me). If the case don't drop in freely, I will resize the case again until it drops in freely or it gets tossed in the recycle bin. You could use the FCD to "push-through" resize the overly bulged case with the knob removed as in
Lee Bulge Buster but not 9mm which is a tapered case and wider at the base).
For me, if an overly bulged case is reloaded, it may not fully chamber in the barrel and I prefer to catch it before I reload it instead of "fixing" the case with the FCD.
OK, back to OP on taper crimping 9mm/40S&W cases.