On seating a bullet, a bulge may form at the bullets base, pushing the brass outward. This is caused by a taper of the loaded round & increasing case wall thickness. The longer the bullet, the deeper the base goes into the case. If the round will chamber in the firearm, its not a problem. The 147 gr is a looooong bullet. It sits quite deep into the case. When that long bullet is forced deeply into the case, it pushes the case walls out giving you a bulge. Hornady's 147 is a boat tail design to help avoid this.
Some other 147gr bullets have a flat base. This drives deep into the case and pushes case walls out, making the bulge. Neck Sizing Handgun Brass - Its possible to only size the part of the neck that holds the bullet. In other words, dont let the carbide sizing ring, size below the bullets base. May or may not work for you. Its a suggestion from an old RCBS news letter.