Before seating your bullet, measure the ID of the neck. Ideally, it should be about .002" or so smaller than the bullet diameter. I think you will find that there is a much larger difference. For one thing cast bullets are generally larger than jacked bullets, which will only aggravate your problem. Get a larger diameter expander ball, one that is about .003" smaller than the bullet diameter you are using. I think your "bulge" will go away. Good Luck and Good Shooting