This is the way the company that made the brass added an extra layer of protection against bullet setback. This is basically an internal cannalure. It may iron out in a few reloads or it may not depending on the hardness of the brass. It is nothing to worry about and load as normal. There are a lot of rimmed pistol rounds (38 SPL, 357, 45 Colt, etc) that are made this way. It never has caused any problems with my reloading them to date.