Okay, You need to retool slightly. Make seating and crimping a 2 step process. Step 1: Set your die 1/8inch too high and adjust seater below the crimp. Seat your set of bullets to the cantilever. Step 2: Raise up the seater and with your first shell inserted slowly lower the die till the crimp is barely making contact. Retract the shell and lower the die 1/8 turn for test crimp. Readjust accordingly. I acknowledge you are using a 3 die set and this would apply to a 2 die set. Look for an obstruction in either die.
