Thread: What causes this

I think you are on the money there mate, what I think iv been doing is taking the case up till it contacts the die to get the correct seating depth, and stopping when it gets hard.
the problem occurs when i push past that point and the opening of the case must contact inside at the top of the die

problem cause seating die set down too far,
hiding the problem dirty case necks and not enough lube(so the contacting of the case is hidden inside the differculty

Ill reset my die next time before I use it again