An internal reset system for paint ball markers. A hammer body as modified rearwardly to include an axial opening to receivably retain the forward head of a reset rod. The forward portion of the reset rod is thus free to reciprocate within the axial opening, but restrained, during the reset phase, when the head of the reset rod internally encounters a flange at the rear of the axial opening. In this phase the reset rod carries the hammer to the reset position, compressing a spring, where it is retained by the trigger sear ready for the next firing. The rear end of the reset rod is affixed to a back block that mechanically connects the modified hammer assembly and the marker bolt. In one embodiment the hammer is modified by a hammer sleeve, attached rearwardly to the hammer body and having an axial opening for the head of the reset rod.