well in the walikng dead it took some times one or towe hits in the head to kill them but could be glitch but what i do know is that for any shotguns in head seem to work good try uninstall and to re-install the addon

I corrected the code a little, but the problem is that the damage from the shotgun somehow does not work, how other damage weapons, if you shoot with a shotgun in a dense and exactly in the center of the face, then the damage passes.