For me, shooting Bloodlines, it has never happened and I have been pretty close more than once - to close (but I am knocking on wood). On a frontal shot the petals will be off long before the bullet could enter through the diaphragm. On broadside shot behind the heart and in front of the diaphragm I have not had one penetrate the diaphragm. Like I said been close a couple of times. But the diaphragm is a pretty tough flexible muscle tissue.