you could have a build up of case lube in the sizer die that could cause damage to the cases but if you're not noticing the damage until after you seat the bullet then the accumulation of case lube in the sizer die is not the issue but if you are seeing some damage after you size then that is an issue. you might have some type of build up or obstruction in your seater die. you might want to take your dies apart and give them a good cleaning. after you let the cases soak in water to remove the lube are you wiping the cases off real good in order to make sure that they are dry and all of the lube is removed if not then over time you may have gotten some case lube build up in you seater die?

If you're not huntin' you're not livin'!!!!!!!!