A filler head for delivering a preselected volume of product to a container, the head having a charging cylinder and a piston movable in the cylinder to define a product chamber therein. Product is delivered under pressure through a passage to the chamber, the piston being movable under product pressure in a direction enlarging the chamber. Adjustable stop means limit chamber enlarging movement of the piston to determine the preselected volume. A plug entering the passage as the piston approaches the end of its discharge stroke restricts the discharge of product to reduce turbulence. A piston valve is movable between the product passage and an outlet passage, in one position interrupting the delivery of product to the chamber for discharge of product from the chamber through the valve to the outlet, and in another position closing the outlet and permitting delivery of product under pressure to the chamber. The piston valve is removable as a unit from the head, for ease of cleaning.