Well, since I stirred up a hornet's nest I figure I should follow-up as to what has occurred. I got some larger balls but had the same experience with a ring shearing off the ball when I loaded each chamber but the ball slipping back and forth in the chamber and jamming up the gun. So I camphered each chamber mouth by maybe .003-.004 and tried the balls again. Now they sheared like they are supposed to, but are firmly seated in the chamber and do not slide in and out.
I appreciate everyone's input and the discussions. I also do not really understand why the little gun was the way it was. Just know what finally fixed the problem. No matter what my calipers may or may not have truly indicated.