Abstract: An automatic firearm such as an automatic pistol having a slide and a thumb-engageable control on each side of the firearm for selectively securing the slide in retracted, inoperative position. This permits the firearm to be operated with equal facility and speed by either a right-handed or a left-handed marksman. A detent for retaining the slide in retracted position is mounted within the frame of the firearm for selective cooperation with a latch. A cross pin mounted for oscillation in the frame of the firearm has a lever mounting the detent fixedly connected thereto. Fixedly connected to one end of the pin outwardly of the frame of the firearm on a first side thereof there is a radially extending first detent control arm. On the other, second end of the pin, on the other side of the frame there is removably attached a second detent control arm, preferably identical with the first control arm, and disposed in the same angular position with respect to the pin.