[Roundsworth]

Extended periods, over an hour, don't seem to yield better results. I just finished cleaning a nasty shell that required some soft brushing after 3 sessions in the undiluted vinegar. I submerged the brass for about 15 to 20 minutes, then hold the shell in a stream of hot water while brushing. The water will come out chunky and black. Sometimes the rough, scaly stuff surrounding the primer pocket is quite tenacious! It would not take much with a blaster and glass beads to clean the bottom of the shell. If you have access to that type of equipment, you could probably just skip the vinegar!