All of the reading that I do states that you HAVE to trim 5.7x28 to lenght before you relaod them the first time. I have an RCBS auto trimmer but they do not make the shellplate for 5.7 or 25 acp. What are you guys using to trim the case lenght on 5.7x28?
You need to size first, then trim.
I grabbed this off of another forum. It was the first result when I Googled "5.7 by 28 trim."
Lee Case Length Gage for Lee Case Trimmer Cutter and Lock Stud Note: Shell holder must be filed down significantly for shell to fit
Lee Case Trimmer Cutter and Lock Stud
RCBS Trim Pro Manual Case Trimmer
Shell Holder for RCBS Trim Pro Case Trimmer available from Elite Ammunition – Special Order
Maybe this will point you in the right direction.