Chapter 10, the Reed ammunition measures exactly or smaller than the chamber cast, but won't go the last 1/16" into the chamber. Since the main cylinder of the case measures correctly, I am assuming that the area behind the neck has not been sized to the real chamber dimension. The neck diameter is safely undersize. I don't have access to a case sizer, so I would like to take advantage of Rocky Mountain Bill's offer to send me some cases to try. I will PM Bill with my address. I am anxious to shoot this gun, thought today would be the day.