A primary piston component for a master cylinder of a hydraulic brake system includes a primary piston housing and an additional piston component, which is configured to be at least partially movable into a cavity of the primary piston housing. An inner piston body extends through the cavity along a central line of the primary piston component. A braking force applied on a brake actuating element is transferable at least partially on the inner piston body, and further on the primary piston housing. The additional piston component is at least partially movable into the cavity between the inner piston body and the primary piston housing, and a brake booster force is transferable at least partially on the additional piston component, and via the inner piston body on the primary piston housing. A method of operating a hydraulic brake system is also described.