A hammer shank and a separate shank butt component for a grand piano hammer assembly with increased rigidity, reduced inertia, and the collateral benefits of increased efficiency of manufacture and maintenance. Hammer shank comprises a long cylindrical member that is connected at one end to a traditional grand piano hammer and at the other end to a novel shank butt. Shank butt comprises: a hammer shank hole, a knuckle slot, a set of two flange attachment holes, and a void area. A traditional grand piano knuckle is attached to the knuckle slot. The shank butt is connected to the repetition flange of the piano. The invention provides the capability for a piano to be played with less touch weight on the keys and therefore provides a more responsive piano keyboard. The invention also allows for full "retrofitability" of hammer assembly into all existing grand piano brands. Embodiments include a composite shank butt that is a molded article and a composite hammer shank that is an extruded or molded article.