The invention relates to a reciprocating-piston liquid meter cylindrical measurement chamber (1) of the type comprising at least one peripheral side wall (3), a lid (4) and a bottom (8), the said bottom (8) supporting a superstructure (9), in the form of an open cylindrical component equipped, near its middle, with a cylindrical peg (10) of a diameter smaller than that of the said superstructure (9) to form, between the internal peripheral surface of the said superstructure (9) and the external peripheral surface of the peg, a circular guideway, the said chamber (1) containing a piston (2) with cylindrical body moved by the liquid flowing inside the said chamber (1), the said piston (2) being internally equipped with a pin coaxial with the said body of the piston, it being possible for this pin to be inserted in the circular guideway so as to guide the piston (2) as it oscillates within the chamber (1). This chamber (1) is characterized in that the peg (10) and the superstructure (9) are produced in the form of a single component so as to guarantee that the said peg (10) and the said superstructure (9) will be coaxial with one another.