Behold the Harrington & Richardson .25ACP Self-Loader, made between 1919 and 1921. Note that while it has a loaded chamber indicator, it is devoid of even the most vestigial sights.
My roommate maintains that the purpose of a firearm like this is to allow for an intended victim to yell from the other side of a door "Don't come in! I've got a gun!" and not be lying.