As I have discussed on several threads, I agree, an FCD is perfectly fine for use with cast bullets. Due to loose tolerances at Lee, some people will have tighter FCDs than others. Mine .45acp fcd is a little tight and swages my .452" cast bullets by .0005"-.001". You can see a little ledge at the case mouth when you pull a bullet and the OD of bullet that was inside the case is slightly less than the exposed portion). In .380/9mm/.38/.357 this doesnt happen with the fcds I have
If there is any effect on accuracy I cant tell. Out of an SR1911 I shoot sub-2" groups at 25yds and cant come close to that with any other caliber handgun I load for.