Forster dies.

Sizing Wolf brass is fine.

Sizing Hornady brass, Crushed the shoulder on one.

Expander won't fit in the neck?
Neck too thick?

Can you set the expander down lower so it is completely through the neck before the neck enter the sizing portion of the die?

Get a long tapered expander. Or make one. Hornady dies have a pointed expander that makes your problem impossible.
And as Gruff said, make sure the expander ball is low enough; this is important on Forster dies more than any other as the ball is way up on the decapping shaft.
Chamfer your brass necks.

Yup this was it.

quote:

Originally posted by Von Gruff:
Can you set the expander down lower so it is completely through the neck before the neck enter the sizing portion of the die?

quote:

Can you set the expander down lower so it is completely through the neck before the neck enter the sizing portion of the die

Been there done that.