An arc tube for a ceramic metal halide lamp includes a hollow first body member (40) that is tapered along a majority of its length to aid in removing the molded component from a pin during assembly. An open end (46) of the first body member has a constant diameter (60) allowing it to be joined to a constant diameter portion (72) of the second body member or end cap (70). The mating constant diameter portions ensure that the hollow first body member can be monolithically joined with the end cap with a reduced level of seal voids.