I just remembered something..I was forming 357 Harret cases from 30-30 brass. and had a box of winchester brass once fired. when I sized it it would spring back enough that cases could not be formed from them. even setting the dies all the way down then1/2 turn more the press would knuckle over and lock. when I would try to chamber a new made case the action would not close,that is how far back the case would spring.. that box of cases had something in the metal that made the cases too springy I finally dumped them as I only had one box of them.. maby you got a box of bad metal in the cases????
