Howard, about 1875 WH Baker began using this locking device and LC Smith continued to use it until 1884. The locking bolt rides horizontally in the bottom of the receiver and is retracted to open the breech by pushing the right trigger forward. A stirrup fits over a spur on the top of the trigger to retract the bolt and a spring extending downward from the top tang supplies the pressure to keep the bolt forward and latched into the barrel lug upon closing.