Starkherz199 is right. I have never seen creating on handgun rounds of my own, but I have had it when doing load work ups for rifle where the pressures are greater. If they are factory ammo, I would not worry too much, but if reloads, then the question is where are you in the min./max. spectrum, what is your seating depth and maybe how heavy is your crimp. Need to look at what may be causing unusually high pressure.