The nose/ogive of the bullet is deformed on seating. This may be caused by- 1. Make sure the bullet is not being crimped to early, requiring more pressure to seat it. Try crimping in a separate operation. Crimping while seating may have an effect on the finished COL. 2. The expander should open the inside of the case so the bullet seats with less pressure. This will help stop the nose getting deformed. 3. The seating stem that contacts the bullet may be of the wrong shape. 4. 38 Spec./357 Mag. Measure the diameter of the bullets, should be no larger than .358" Then measure the expander diameter, should be about .356" 5. A defective seating die? The inside die diameter is to small. On seating the case/bullet is being sized. The nickel brass wall thickness would have to be greater than the brass case. Measure both over a seated bulllet & compare. The fix is to remove metal from the die in front of the crimping area. Or return die for replacement.