What conversion makes an ar-15 full auto or illeagl?

[sicilian0]

When installing an m16 parts kit on an ar-15 whta makes it illegal by class III standards or to fire full auto? If i were to install the m16 trigger, selector switch, disconnector and hammer with j rig do these replacement parts alone make the ar fire full auo or become an illegal class 3 weapon? Or is it essential to install athe gi sear and bore out tohe reciever for it to fit for the weapon to fire full auto or become a class 3 weapon illegal by tf standards? So if i were 2 use these m-16 replacement parts but not possess or install a gi sear am i still in the realm of semi-auto fire and a non class 3 weapon leagal by atf standards? Im asking this because i dont want 2 make the mistake of creating an illegal weapon. Please let me know if u r familiar with the installation of these parts the reaction or change they cause at all in the gun and the legal ramafications of doing so. Another word installing these parts with out a gi sear doesn't the ar-15 remain semiautomatic and a non class 3 weapon?