tried out my new RCBS 8x57 from 30-06 forming die. Formed and marked 53 pieces. Cut a couple down and went to trim with my Lee Quick Trim and the brass just spins. No o rings. Finally found the size online and will hopefully be able to locate some 12mm o rings of a workable diameter tomorrow and be able to trim the brass. Having to cut down with a hacksaw, going to see if I can locate a really fine tooth blade. Or may try my tubing cutter. But suspect that would leave an inside ring.
I was able to rig enough pressure to trim two cases, and confirm that the homemade 8mm will cycle at COAL for the bullet I use.