I also forgot about the mandrels needing to be polished. Seat the die exaclty to how lee explains it in the instructions also are you exerting enough force lee says you need a minimum of 25 lbs of pressure on the press lever. and if you are still having the problem then turn the die in an additional 1/8 to a 1/4 turn if that doesnt work then polish the mandrel. if you dont want to polish the mandrel yourself get in touch with lee and they can make a custom mandrel for you for 5 bucks. But again im 100% positive its either a misadjusted die or possibly operator error. these collet dies work differently then typical dies. as lee says it in the owners manual "forget everything you know about die adjustment and follow the instructions."