Ignoramus8862 wrote:

The momentum would be the same as the
rifle's recoil (which is painful), only transferring more energy
because of higher speed of the affected area of the vest, compared to
the speed of rifle moving backwards.

Is the bullet a rocket?
50% of the energy go into the bullet, the other half into the gun.
E = m/2 v^2. That is true for both the bullet _and_ the gun.

Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de