US Patent 8438774 Pistol cocking assistive device

At least one cam lock and an opposing structure form a compression channel for receiving and engaging a pistol slide. When the pistol is moved in a certain direction through the compression channel, the one or more cam locks and opposing structure engage the pistol's slide and translate some of the forward motion force into a compressive force on the sides of the slide. At a point where the compressive force overcomes the force of the main spring of the pistol, the pistol frame driven by the user moves forward relative to the slide, thereby racking the slide of the pistol.