I've seen this when the seating die was turned down too far and was over-crimping the case.
Start here... I've done it
run an empty case into the seating die, If it touches or crimps you've found your problem
"Camping places fix themselves in your mind as if you had spent long periods of your life in them. You will remember a curve of your wagon track in the grass of the plain like the features of a friend." Isak Dinesen
