Abstract: An ejection port gun lock includes an elongated body and a slide member which is slidably affixed to the body to move along a slide path (with the slide path being oriented generally parallel to the length of the body) between an engaged position within a gun ejection port and a disengaged position in the ejection port. A locking member is provided on the body adjacent to the slide path, and the locking member is movable between a locked position wherein it extends into the slide path to engage the slide member, and an unlocked position allowing motion of the slide member.