The SWATriplex-18 was a bullpup dual-fed shotgun designed by John W. Winter in the 1970's. It was semi-automatic and incorporated twin tubular magazines. The design was unsuccessful and the SWATriplex-18 was not mass-produced. It is thought that the main reason for the SWATriplex-18's failure was that it was too far ahead of it's time. However, more modern Kel-Tec KSG shotgun incorporated some of the SWATriplex-18's features, and has been far more successful.