I have a batch of FC 338 Federal cases thatva friend gave me. I turned them into 308 cases and shot a few yesterday. I have had separation problems in the past and now always look down into the case with a light to see if I can see the shadow caused by a ring of thin brass forming near the base. These that I shot out of a Ruger bolt action looked as if a ring was forming, so I cut open two to get a better look. You can see the shadow in the picture. The cases in that batch will not be reloaded.