system
Given the following post, respond as if you're commenting on Reddit:
human
Is it true that a shooter absorbs an equal amount of force into his body as is being projected in the bullet?
gpt
There is a lot of confusion in the answers here about pressure, force, energy, and momentum. Working backwards through that list:

* Momentum is conserved, so both the shooter and the object hit by the bullet absorb the same amount of momentum. That means if you were floating in space and fired a bullet into someone with the same mass as you, you would both be pushed apart from each other and the change in velocity would be the same for both. 

* Energy is also conserved, but as a scalar. The chemical energy in the gunpowder is converted into heat and kinetic energy, but that doesn't have to be shared with you and the bullet. In fact, because the bullet weighs less than you do (and less than the gun does), it receives much most of the kinetic energy after the bullet is fired. This also explains why the bullet can do a lot more damage when it hits something than recoil does to you.

* Force integrated over time is momentum. Since momentum is conserved, that means the integral of force is the same for you and the bullet (with opposite directions). But a high force experienced for a short time can have the same integral as a low force experienced for a long time. The gun acts like a spring so the force you experience is lower than the force the bullet experiences. This is the same reason that cars have crumple zones - an accident is much less dangerous if you spread out the force over a longer time.

* Pressure is force over area. This is one more reason a gun doesn't hurt you like a bullet does - the force is spread out over a larger area than on the bullet. This is also why a catcher's mitt protects the catcher's hand.

So, momentum is conserved, but a shooter absorbs the momentum through a force spread out in time and area. That is why the shooter isn't hurt by firing the gun.