|Name||The Equalizer or the Hammurabi|
|Manufacturer||God aka Chuck|
|Powers||Can kill anything.|
|Location/Owners||In the Winchesters' possession|
|Episodes|| 14.20 Moriah|
15.01 Back and to the Future
So, this doesn't so much fire bullets as it sends a wave of multidimensional energy across a perfectly balanced quantum link between whoever's shooting it and whoever they are shooting at.
This weapon was created by Chuck to kill the Nephilim Jack Kline. Chuck's suggested names for the weapon are the Equalizer or the Hammurabi. Hammurabi was a Babylonian King best known for having issued a code of law, known as the Code of Hammurabi.
The gun does not fire bullets, instead employing a wave of multidimensional energy using a balanced quantum link between the target and the shooter, causing whatever happens to the target to also happen to the shooter. According to Chuck, the gun is capable of killing anything. Castiel proves to be unable to heal the wound it inflicted upon Sam, stating that the wound has an energy he has never felt before. The shot also has a negative effect on God, who in His wounded state is no longer at full strength or complete, and is afraid. The bullet creates a link between Sam and God, causing Sam to feel pain from the wound when God does.
Chuck presents the gun to the Winchesters and Castiel as the only weapon capable of killing Jack Kline. However, He warns that whatever happens to the target also happens to the shooter, meaning that whoever kills Jack will die as well. Chuck explains that this is why He can't kill Jack -- because if He dies, the Universe ends.
In a cemetery, Dean confronts Jack with it, but can't bring himself to kill Jack, instead dropping the gun. This enrages Chuck, who demands Dean pick up the gun and kill Jack, going so far as to try and entice Dean by promising to bring Mary back. But when Dean still refuses, He begins smiting Jack. As Chuck is about to leave, Sam grabs the weapon and shoots Chuck, hitting Him in the shoulder and injuring himself at the same time. However, it fails to cause Chuck any real harm, only angering Chuck enough that He decides to end the world, unleashing the souls of Hell upon the Earth.
Sam continues to carry the wound he got from shooting Chuck. After healing Sam's knife wound from John Wayne Gacy, Castiel attempts to heal the gun shot, but receives strange visions of Sam and tells him that he cannot heal it as the wound is emitting an energy he has never felt before. Dean later treats the wound and notices that the bullet has no corresponding exit wound.
Chuck is revealed to be suffering negative effects from Sam shooting Him with the Equalizer. Amara senses that Chuck is now no longer complete, not at full strength, and afraid. Chuck and Sam are shown to share a link, with Sam feeling the pain Chuck does when He touches the wound. Amara later states that Chuck has been severely weakened and while He can still do "a few parlor tricks," He is trapped on Earth and can't leave or heal His wound without her help. Amara refuses to help Chuck, likening His state to when He once trapped her.
Sam has a nightmare in which he has continued drinking demon blood. Dean is battling demons in the Bunker. When Dean confronts Sam, and talks about how he killed Jody and Bobby, Sam kills him.