Mp40guy, lee sales a bulge buster die and it might help you. What projectiles are you loading. I load coated 180s and sometimes have this issue maybe 10 out of 1000 rds. When I load jacketed bullets almost always they all case gage. Cast lead bullets are sized different from jacketed bullets. My rounds usually have a little hump where the bullet is seated but it never really affects if mine pass the gage. If your crimp is off it could play a role as well.