[IllinoisCoyoteHunter]

BDS-

What is the purpose of the larger carbide rings??? What will it do??? Keep from swaging lead bullets?? I can guarantee as long as your sizer die is set up properly that the enlarged carbide ring will never touch the case. The die will only apply a taper crimp....and you can do this with the seating die.

As stated above the carbide ring on the sizer die is SMALLER than the carbide ring on the FCD.

In conclusion:

I guess it just comes down to whatever works for you. If it works, use it. I, fortunately, have never found a use for it.