KyleC,
I have a batch of Win cases that have been fired about 5 times in my 700 and re-sized with about .002 shoulder set back, in other words just like a rimless case. The set up you used is just about guaranteed to result in excessive sizing and subsequent case stretch. Get a RCBS case mike or similar tool and set your die to set the shoulder of cases fired in your rifle back .002-003". This has (obviously) worked well for me. Good shooting!