|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.
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.
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 is afraid. Chuck and Sam are shown to now share a link with Sam feeling the pain Chuck does when he touches the wound.