A sand knock-out head clamping assembly of a casting vibratory apparatus for engaging a casting to be vibrated is provided. The assembly includes a holder configured to be releasably mounted to a vibratory mechanism of the vibratory apparatus. The holder includes a holder body having a first face in contact with the vibratory mechanism and a second face opposite the first face. The holder body includes an engagement member extending outwardly from the second face. An insert is removably mounted only to the holder. The insert is configured to at least partially receive the engagement member.