bullet seating question

[RM]

I'm reloading .357 Magnum with Zero 158 g JSP bullets. I'm using a Hornady seating die, seating and crimping in one step. About once in every 10 rounds, the seating stem and sleeve are pulled out the die and have to be reinserted. Sometimes the alignment sleeve is stuck to the bullet. There is a slight crimp on the ogive after the bullet is seated. Any thoughts on what causes this and how to correct it? Thank you!

 

[KAB55]

I have that happen when I'm loading lead. The lube & lead from the bullets builds up in the seat die and pulls the sleeve and stem out. Never had it happen with a jacketed bullet. A lite cote of gun oil on the inside of the sleeve helps, but you need to clean the sleeve out every 1-200 rounds if your loading lead.