O.K., this may be of some help to you.I had a natter with a RCBS tech some time ago, having somewhat similar problems.
What he told me was:
1. Set the seat/crimp die like thus: run a trimmed,sized, expanded case into the press with the ram full up. If it is a compound press, the ram will "cam over", so you need to take that into consideration in your adjustments
2. screw the die into the press until the crimp ridge gently contacts the case mouth. The case may need reexpanding. Screw the lock ring down against the press, and slightly tighten the lock screw so you don't lose your adjustment. Unscrew the seat/crimp die body 1/2-1 inch.
4. Unscrew the seating stem so it will not contact your bullet until you want it to.
5.Place a bullet in a properly prepared case. A new case will insure the case will still accept the bullet.
6. Raise the ram, and screw the seating stem down till it contacts the bullet nose, keep screwing the seater plug down till your bullet is at your chosen depth/cartridge length.
7. Unscrew the seater plug again, and screw the die body down to the lock ring. RCBS said that factory crimps are in fact, overcrimps. No more than a half-turn will provide sufficient crimp, sez he, because case mouth tension is what really holds the bullet. I prefer to crimp until I have very little or no "hang up" on the case mouth/crimp when I lightly run my fingernail down. NOW, check your cartridge for overall length, and crimp. Hint: If you see what looks like a good crimp, check at the top of the brass, and see if there is a faint line, and a very tiny "lip" above the crimp. This means that there is too much crimp, and the brass has run under the crimping ridge too far. Adjust your crimp till it disappears.
8. All this time, the seater plug should not have contacted the bullet. If the overall length needs adjusting, do it.
9. Tighten everything down, run a cartridge or two to see everything is proper, then load away!
I hope I haven't told you how to build a whole bicycle, when all you really wanted was to know how to change a tire!

Oh, BTW, I have had Lyman, Lee and RCBS dies, and have had really god service from RCBS. The jury is still out on the Lee FCD.