"To get a perspective on how an AR-15 bullet differs from a 9-millimeter bullet, the 60 Minutes team spoke to Don Deyo, a former paramedic and Green Beret who witnessed mass casualties up close on the battlefield. He demonstrated the difference in bullets by shooting rounds into a cut of pork that's similar in size to an average adult human thigh. At first glance, the two rounds looked similar, both leaving an entry wound that's nothing more than a tiny hole in the flesh. But flip the pork over, and the difference is stunning. The 9-millimeter exit wound was small, without much damage to the surrounding area. The AR-15 exit wound left an enormous, gaping hole and shattered the surrounding bone. Those bone fragments, Deyo explained, become projectiles that create further tissue damage.... After an AR-15 style rifle bullet blasts a large cavity through soft tissue, blood pressure then pumps that cavity with blood, causing many victims of AR-15 shots to bleed out before rescue workers can reach them."