The Bullet physics should effect the bullet on distance, drop and penetration.

And the damage is based on where it lands or hits. For example If the bullet hits a british or german's foot, it should reduce the speed by 11% on walking and running and also counts on the legs.
If a bullet hits the left arm, accuracy is reduced by 15% when used bolt-action rifles,
pistols, grenades, telocscope/binoculars, and machine guns. For the right arm, firing
speed,reloading and using the bolt-action is reduced by 17.5%. If a bullet hits a british or a
german soldier's chest, somach, back, for head(unprotected areas) it's an instant kill.