With monos, you either need to push them fast or hit some bone for them to really do damage. If not they just perform as advertised, the front mushrooms back, doubling in size and they zip on on through......
sounds like in your case, from an elevated position, you hit high and rear lung and exited midish lung. Do to the way the lungs are built, High and rear lung does not bleed as much as low lung and that body cavity has to fill up to your exit hole before blood pours out.
I would suggest aiming FOR dead center of the shoulder blades with monos and you will be pleased with the results.
