Black Barrel

Black Barrel is a weapon carried by Gun God in Notes, and is in fact what gave him that nickname. It was excavated by him after his family was killed by Type-Jupiter.

=Abilities= According to Notes, Black Barrel is made of a special mineral that counters Gin. Because of that, it cannot be used by any creature that intakes Gin into their bodies. In Notes, that rules out everybody except unmodified humans. In fact, the weapon is more effective, the more Gin it's target carry. For that reason, it was called 'a gun that kills gods', and was very effective against Types.

Gun God took down Type-Venus using Black Barrel, and later used it in a mission against Type-Saturn.

=Appearance= In Melty Blood, Sion carries a handgun named Black Barrel Replica that is presumably connected with Black Barrel of Notes. It is questionable whether Black Barrel itself is a handgun, as Gun God is mentioned to have modified it into a form that could be used for sniping, which would be difficult to perform on a handgun.

This also implies Black Barrel originates from Atlas.

=References=
 * 'Notes' translation by Evospace, edited by Raeinus, from Beast's Lair