The size of the head has nothing to do with the hardness of the bite,coralation of bite has to due with symmetrical skull and jaw confiquration.length of muzzle creates harder bite due to sissor bite and leverage in bite design.I.E. an overly long snout with a small head or an overly large head with a short muzzle does not insure a greater bite. just as people beleive that pit bulls have a locking jaw not the case,its hardness of bite thats all.................thats why there is bloodlines with in.. Realdogs