My bad. I meant to say exited from below his right nipple. I've fixed it if you want to respond.
Sorry, John. I should have asked you first if that was a mistake. In reading it over I can see that the rest fits with you intending to say “exited”.
The key to understanding the second bullet is to understand why JBC felt such a forceful impact where the bullet entered. That impact requires the bullet to undergo a significant change in momentum at the point of impact. The bullet didn’t stop there and it did not penetrate the fifth rib at the point of impact. That occurred farther along the rib. Since the bullet little damage at the point of initial impact, it did not lose much energy, hence speed, there. The bullet had lots of energy after that initial impact because it took out the last 10 cm of the rib driving bone shards into the lower right lung and then had enough energy to fracture the radius in several pieces.
So the momentum imparted by the bullet to the fifth rib did not result from a significant and sudden loss of its speed at the point of impact. Rather the momentum transferred to the body at the point of impact was due to a sudden change in direction of the bullet at the point of impact. This means the bullet struck the fifth rib at much more than a shallow glance. It struck the fifth rib solidly at an angle much closer to the normal or perpendicular to the surface of the rib. The fact that the rib fractured farther up the rib close to the spine supports this forceful, more normal impact angle. Since it did not penetrate the rib at that point, it changed direction to follow along the rib. Since force is equal the time rate of change of momentum (Force=change in momentum/time period) the sudden change in direction requires a large force applied by the body to the bullet at that point with an equal and opposite force of the bullet to the body at the point of impact.