Necks are very thick when you neck down and form brass to the 7x57. This will put a death grip on the bullet if you are not using a bushing sizing die. Anneal necks after you neck them down.
I annealed them before I resized them. Since it was .270 brass the necks should of been stretched and not shrunk. I have not yet loaded them. I guess I will know then for sure.
kwg