The Bolt Action Mariana and Palau Campaign book introduced the Mark IV twin Oerlikon 20mm auto cannon for US player. In the pacific the USMC employed this unique twin 20mm cannon to provide AA defence. The platform was unlike the pedestal mounted twin Oerlikons employed by the U.S. Navy, as the field mount needed to ensure its own stability and not rely on the mammoth weight of a warship to provide a secure mount. The gun was normally loaded with sixty round drums, and had two gunners, one on each side of the twin mount.
This .stl pack from Deweycat includes basic and pre-supported .stls for the gun, plus two seated gunners and an optional gun 110mm round base. The gunner stls provide the body without heads, as it is intended that appropriate heads be added from your army bits.