How to manufacture an "out of round" chamber??? A two flute "reamer" may produce a tri-lobal hole, A single point tool can possibly produce an elliptical hole. (Basically, the number of lobes is equal to the number of cutting edges plus one.) The typical reamer hes anywhere from 6 to 8 cutting edges, so making a measurably out of round chamber is HUGELY unlikely! The same for "banana shaped" chambers- reamers don't bend- they either break or make an enlarged entry zone...

Crazy stuff!