The Pancor Jackhammer is a bullpup select-fire (semi-automatic and automatic) shotgun manufactured by the Pancor Corporation. While there were some existing prototypes, the weapon was never mass produced. The MK3, or Mark 3, was a third variant protoype of the weapon. The MK3 is categorized as a shotgun in the Rainbow Six universe. The MK3 only appears in Tom Clancy's Rainbow Six 3: Raven Shield.