Thanks for the replys. No, I do have the appropriate brass for the caliber and I have this problem with the 357, 44 Mag and 45 Colt.
The dies for my pistols are different from my rifle crimp dies. The rifle dies have an open top and a slotted crimp tub. The pistol dies adjust with a shaft with threads. I have no problems with the rifle dies, even with the cast loads for the 45-70. Only with cast loads in the revolvers is the problem showing up. Maybe I am screwing the shaft down too far, although I am doing right now exactly what the directions say do.
What is happening is that I set the seating die for an OAL of say, 1.600. After the crimp the OAL is 1.580 or thereabouts. This is driving me nuts.