Abstract: A wire line core sample retrieval apparatus includes an improved core barrel head assembly having a special lifting collet designed to engage with an overshot. The head assembly includes improved latches and cam means designed to positively retract them when lifting forces are applied to the lifting collet. The overshot includes a special locking collar and associated assembly to provide positive locking engagement with the lifting collet as well as providing easy locking and unlocking of the overshot from said lifting collet either in the well hole or on the surface.