Не доделка!

#include <amxmodx>

public plugin_init(){
 register_forward(FM_SetModel, "set_model", 1);
}

public set_model(ent, model[])
{
 if(pev_valid(ent) && equal(model, "models/w_deagle.mdl", 31)){
  new id = pev(ent, pev_owner)
  if(new_deagle[id]){
   engfunc(EngFunc_SetModel, ent, "models/w_deagle_new.mdl")
   new_deagle[id] = false
  }
 }
}