Why do Lee dies get slagged so much here

[ported45]

I like Lee's collet neck sizers, but standard bottle-neck sizing dies I do not trust. I got a set for 7mm Mag to reload for a buddy and was trying to reload someone else's once-fired brass. The Lee sizing die would not size down enough to let the brass chamber in his rifle. Ordered a set from Hornady and problem was fixed.