This effect is important in every video having shooting guns.
It looks easy but demands precise work of the professional. The bullet hit has to correspond precisely to the gun shot and actor. It also has to interact with material so it is important to take into consideration textures, composition and action itself.
Safety is very important, so this effect takes a lot in planing. Our experience is based in many tests in the workshops and long filming hours.
Always check licences and certificates for persons and materials providing the effect and never do it at home!