A holster for securing a pistol having a barrel with a chamber, a muzzle, a slide having a front and rear portion, includes (a) an open-bottom enclosure sized to accommodate the slide, wherein a cavity defined in a front portion of the enclosure is sized to receive the muzzle but not allow the slide to enter therein; (b) a securing member pivotally attached within the enclosure near a rear portion thereof and shaped to correspondingly mate with a rear portion of the slide; (c) a lever disposed externally to the enclosure and attached via a connecting member to the securing member; (d) a spring disposed between an interior surface of the enclosure and the securing member; and (e) a protuberance extending from the interior surface of the enclosure and sized to be received into the chamber when the pistol is secured within the enclosure.