Ran into a problem while attempting to full-size some one-time fired Graf &Sons brass with a new Lee die. What happens is that a length-wise dimple is
created in the shoulder/neck area. I've tried to avoid this by performing the process very slowly while several times backing off and turning the brass a
few degrees at a time, but to no avail. I seems to appear in the final part of the stroke. Also, the brass was lubed ahead of time.
Would greatly appreciate some advice on this. Is it perhaps a faulty die?
Here's a picture:


