Given Newton’s law of equal and opposite forces, why does a rifle bullet hitting body armour still cause serious damage to the person being shot, but the recoil of the gun doesn’t cause harm to the shooter?

Question

Edit *solved*

Thanks for all your responses, I understand now

For clarification:
I’ve heard a lot about the limitations of personal armour, and how it will still result in broken ribs and potential blunt force organ damage even if it stops penetration.
But if it’s spreading the force out over a large area, (arguably larger than the stock of the gun) how is that impact worse than the equal and opposite impact of the rifle recoiling into the shooter’s shoulder?

In: Physics

Answer 1

The gun accelerates the bullet over the length of the rifle’s barrel. On the “receiving” end, the bullet is decelerated by body armor in the length of the bullet. Since energy is mostly conserved, dumping the energy in a much shorter distance gives a much larger pulse of force.