Abstract: In a Luger pistol equipped with a toggle hold open mechanism, a small portion of one of the frame side rails is milled out in the vicinity of the sear bar slide to receive a new L-shaped release lever engageable at one end with the gun's hold open latch. The original sear bar slide is replaced by a modified form engageable with both the thumb safety lever and with the release lever in such manner that as the safety lever is moved to "safe" position, the release lever disengages the hold open latch from the breech block and allows the toggle mechanism to move forwardly and downwardly into closed position. Concurrently, the trigger mechanism is automatically locked against firing.